Página 9 dos resultados de 13330 itens digitais encontrados em 0.037 segundos

‣ Amino acid sequence and crystal structure of BaP1, a metalloproteinase from Bothrops asper snake venom that exerts multiple tissue-damaging activities

Watanabe, L.; Shannon, J. D.; Valente, R. H.; Rucavado, A.; Alape-Giron, A.; Kamiguti, A. S.; Theakston, RDG; Fox, J. W.; Gutierrez, J. M.; Arni, R. K.
Fonte: Cold Spring Harbor Lab Press, Publications Dept Publicador: Cold Spring Harbor Lab Press, Publications Dept
Tipo: Artigo de Revista Científica Formato: 2273-2281
Português
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BaP1 is a 22.7-kD P-I-type zinc-dependent metalloproteinase isolated from the venom of the snake Bothrops asper, a medically relevant species in Central America. This enzyme exerts multiple tissue-damaging activities, including hemorrhage, myonecrosis, dermonecrosis, blistering, and edema. BaP1 is a single chain of 202 amino acids that shows highest sequence identity with metalloproteinases isolated front the venoms of snakes of the subfamily Crotalinae. It has six Cys residues involved in three disulfide bridges (Cys 117-Cys 197, Cys 159-Cys 181, Cys 157-Cys 164). It has the consensus sequence H(142)E(143)XXH(146)XXGXXH(152), as well as the sequence C164I165M166, which characterize the metzincin superfamily of metalloproteinases. The active-site cleft separates a major subdomain (residues 1-152), comprising four a-helices and a five-stranded beta-sheet, from the minor subdomain, which is formed by a single a-helix and several loops. The catalytic zinc ion is coordinated by the N-epsilon2 nitrogen atoms of His 142, His 146, and His 152, in addition to a solvent water molecule, which in turn is bound to Glu 143. Several conserved residues contribute to the formation of the hydrophobic pocket, and Met 166 serves as a hydrophobic base for the active-site groups. Sequence and structural comparisons of hemorrhagic and nonhemorrhagic P-I metalloproteinases from snake venoms revealed differences in several regions. In particular...

‣ DNA sequence, polymorphism, and mapping of luteinizing hormone receptor fragment (LHCGR) gene in Great Dane dogs

Santos, S. E. C.; Escobar, H. Murua; Sider, L. H.; Winkler, S.; Aoki, S. M.; Milazzotto, M. P.; Campagnari, F.; Vannucchi, C. I.; Bullerdiek, J.; Nolte, I.; Garcia, J. F.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 74-75
Português
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‣ Sequence-Specific Binding of Human Immunodeficiency Virus Type 1 Nucleocapsid Protein to Short Oligonucleotides

Fisher, Robert J.; Rein, Alan; Fivash, Matthew; Urbaneja, Maria A.; Casas-Finet, José R.; Medaglia, Maxine; Henderson, Louis E.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /03/1998 Português
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We have analyzed the binding of recombinant human immunodeficiency virus type 1 nucleocapsid protein (NC) to very short oligonucleotides by using surface plasmon resonance (SPR) technology. Our experiments, which were conducted at a moderate salt concentration (0.15 M NaCl), showed that NC binds more stably to runs of d(G) than to other DNA homopolymers. However, it exhibits far more stable binding with the alternating base sequence d(TG)n than with any homopolymeric oligodeoxyribonucleotide; thus, it shows a strong sequence preference under our experimental conditions. We found that the minimum length of an alternating d(TG) sequence required for stable binding was five nucleotides. Stable binding to the tetranucleotide d(TG)2 was observed only under conditions where two tetranucleotide molecules were held in close spatial proximity. The stable, sequence-specific binding to d(TG)n required that both zinc fingers be present, each in its proper position in the NC protein, and was quite salt resistant, indicating a large hydrophobic contribution to the binding. Limited tests with RNA oligonucleotides indicated that the preferential sequence-specific binding observed with DNA also occurs with RNA. Evidence was also obtained that NC can bind to nucleic acid molecules in at least two distinct modes. The biological significance of the specific binding we have detected is not known; it may reflect the specificity with which the parent Gag polyprotein packages genomic RNA or may relate to the functions of NC after cleavage of the polyprotein...

‣ Changes in DNA Base Sequence Induced by Gamma-Ray Mutagenesis of Lambda Phage and Prophage

Tindall, K. R.; Stein, J.; Hutchinson, F.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1988 Português
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Mutations in the cI (repressor) gene were induced by gamma-ray irradiation of lambda phage and of prophage, and 121 mutations were sequenced. Two-thirds of the mutations in irradiated phage assayed in recA host cells (no induction of the SOS response) were G:C to A:T transitions; it is hypothesized that these may arise during DNA replication from adenine mispairing with a cytosine product deaminated by irradiation. For irradiated phage assayed in host cells in which the SOS response had been induced, 85% of the mutations were base substitutions, and in 40 of the 41 base changes, a preexisting base pair had been replaced by an A:T pair; these might come from damaged bases acting as AP (apurinic or apyrimidinic) sites. The remaining mutations were 1 and 2 base deletions. In irradiated prophage, base change mutations involved the substitution of both A:T and of G:C pairs for the preexisting pairs; the substitution of G:C pairs shows that some base substitution mechanism acts on the cell genome but not on the phage. In the irradiated prophage, frameshifts and a significant number of gross rearrangements were also found.

‣ Isolation and characterization of cDNA clones for Humly9: the human homologue of mouse Ly9

Sandrin, M.; Henning, M.; Lo, M.; Baker, E.; Sutherland, G.; McKenzie, I.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Artigo de Revista Científica
Publicado em //1996 Português
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Ly9 is a mouse cell membrane antigen found on all lymphocytes and coded for by a gene that maps to chromosome 1. We previously described the isolation and characterization of a full-length cDNA clone for mouse Ly9. Using cross-species hybridization we isolated cDNA clones encoding the human homologue Humly9. Analysis of the predicted protein sequence suggests that the extra-cellular portion of the Humly9 molecules is composed of four Ig-like domains: a V domain (V) without disulphide bonds and a truncated C2 domain (tC2) with two disulphide bonds, a second V domain without disulphide bonds and a second tC2 with two disulphide bonds, i.e., as V-tC2-V-tC2. The gene encoding Humly9 was mapped to chromosome 1 by analysis of human/hamster hybrids, and more specifically to the 1q22 region by in situ hybridization. The protein sequence data support the view that Humly9 belongs to the immunoglobulin-superfamily subgroup which includes CD48, CD2, and LFA-3.; Mauro S. Sandrin, Margaret M. Henning, Michael F. Lo, Elizabeth Baker, Grant R. Sutherland, Ian F. C. McKenzie

‣ Bovine latent transforming growth factor β1-binding protein 2: molecular cloning, identification of tissue isoforms, and immunolocalization to elastin-associated microfibrils; Bovine latent transforming growth factor beta 1-binding protein 2: molecular cloning, identification of tissue isoforms, and immunolocalization to elastin-associated microfibrils

Gibson, M.; Hatzinikolas, G.; Davis, E.; Baker, E.; Sutherland, G.; Mecham, R.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em //1995 Português
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Monoclonal antibodies to fibrillin 1 (MP340), a component of elastin-associated microfibrils, were used to screen cDNA libraries made from bovine nuchal ligament mRNA. One of the selected clones (cL9; 1.2 kb) hybridized on Northern (RNA) blotting with nuchal ligament mRNA to two abundant mRNAs of 9.0 and 7.5 kb, which were clearly distinct from fibrillin mRNA (10 kb). Further library screening and later reverse transcription PCR by the rapid amplification of cDNA ends (RACE) technique resulted in the isolation of additional overlapping cDNAs corresponding to about 6.7 kb of the mRNA. The encoded protein exhibited sequence similarity of around 80% with a recently identified human protein named latent transforming growth factor beta 1 (TGF-beta 1)-binding protein 2 (LTBP-2), indicating that the new protein was bovine LTBP-2. This was confirmed by the specific localization of bovine LTBP-2 cDNA probes to human chromosome 14q24.3, which is the locus of the human LTBP-2 gene. The domain structure of bovine LTBP-2 is very similar to that of the human LTBP-2, containing 20 examples of 6-cysteine epidermal growth factor-like repeats, 16 of which have the consensus sequence for calcium binding, together with 4 examples of 8-cysteine motifs characteristic of fibrillins and LTBP-1. A 4-cysteine sequence which is unique to bovine LTBP-2 and which has similarity to the 8-cysteine motifs was also present. Antibodies raised to two unique bovine LTBP-2 peptides specifically localized in tissue sections to the elastin-associated microfibrils...

‣ Cloning of the sulphamidase gene and identification of mutations in Sanfilippo A syndrome

Scott, H.; Blanch, L.; Guo, X.H.; Freeman, C.; Orsborn, A.; Baker, E.; Sutherland, G.; Morris, C.; Hopwood, J.
Fonte: Nature Pub. Co. Publicador: Nature Pub. Co.
Tipo: Artigo de Revista Científica
Publicado em //1995 Português
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Sanfilippo A syndrome is one of four recognised Sanfilippo sub-types (A, B, C and D) that result from deficiencies of different enzymes involved in the lysosomal degradation of heparan sulphate; patients suffer from severe neurological disorders. The Sanfilippo syndrome sub-types are also known as mucopolysaccharidosis (MPS) type III (MPS-IIIA, B, C and D), and are part of the large group of lysosomal storage disorders. Each of the MPS-III types is inherited as an autosomal recessive disorder with considerable variation in severity of clinical phenotype. The incidence of Sanfilippo syndrome has been estimated at 1:24,000 in The Netherlands with MPS IIIA (MIM #252900) the most common. MPS-IIIA is the predominant MPS-III in the United Kingdom, and has a similar high incidence to that found in The Netherlands (E. Wraith, personal communication). There is a particularly high incidence of a clinically severe form of MPS-IIIA in the Cayman Islands with a carrier frequency of 0.1 (ref. 4). Due to the mild somatic disease compared to other MPS disorders there is difficulty in diagnosing mild cases of MPS-III, hence Sanfilippo syndrome may be underdiagnosed, especially in patients with mild mental retardation. Here, we report the isolation...

‣ Luteinizing hormone/chorionic gonadotropin bioactivity in the common marmoset (Callithrix jacchus) is due to a chorionic gonadotropin molecule with a structure intermediate between human chorionic gonadotropin and human luteinizing hormone.

Simula, A.; Amato, F.; Faast, R.; Lopata, A.; Berka, J.; Norman, R.
Fonte: Society for the Study of Reproduction Publicador: Society for the Study of Reproduction
Tipo: Artigo de Revista Científica
Publicado em //1995 Português
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Chorionic gonadotropin (CG), a pregnancy-specific heterodimeric hormone found in primates, is responsible for CL rescue with pregnancy maintenance. Of the primates, the human and baboon gene sequences are the only structures so far determined. In order to study the structure and function of CG in other primates, we have isolated and sequenced the coding regions for the two subunits of marmoset CG (mCG) by the reverse transcription/polymerase chain reaction method. Study of multiple clones confirmed a high degree of homology with the human sequences (88% and 80% for the alpha and beta nucleotide sequences, respectively). Marmoset CG alpha has an extra four amino acids compared to hCG alpha, whereas the mCG beta sequence has a 3-bp deletion that maintains the reading frame and C-terminal amino acid sequence. Most of the differences between hCG beta and mCG beta peptides occur in the C-terminal region, which includes the loss of two of the O-linked glycosylation consensus sequences and the presence of an N-linked glycosylation consensus sequence. When mCG alpha and beta were co-expressed in CHO cells, assembly of biologically active hormone was confirmed by induced steroid secretion by MA10 cells. Partially purified mCG beta was used to raise anti-mCG antibodies. To date...

‣ The Escherichia coli retrons Ec67 and Ec86 replace DNA between the cos site and a transcription terminator of a 186-related prophage

Dodd, I.; Egan, J.
Fonte: ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS Publicador: ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS
Tipo: Artigo de Revista Científica
Publicado em //1996 Português
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Retrons are unusual, reverse transcriptase-encoding elements found in bacteria. Although there are a number of indications that retrons are mobile elements, their transposition has not been observed. The Escherichia coli retrons Ec67 and Ec86 are different retrons inserted at the same site and we have further characterized this site in search of clues to the mechanism of retron transposition. We confirm, by extending previous sequence analysis, that Ec67 and Ec86 are inserted into prophages related to coliphage 186. Comparison with the recently published sequence of the 186 96-2% region indicates that the retrons have replaced approximately 180 bp of DNA between the phage cohesive end site (cos) and the transcription terminator of a phage DNA-packaging gene. These features--DNA replacement at the insertion site and the location of retron junctions near transcription terminators or DNA cleavage sites--are shared with other retrons and suggest ways in which retron transposition might have occurred.

‣ A putative pathway for perosamine biosynthesis is the first function encoded within the rfb region of Vibrio cholerae O1

Stroeher, U.; Karageorgos, L.; Brown, M.; Morona, R.; Manning, P.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //1995 Português
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The first four genes (rfbA,B,D,E) of the rfb region of Vibrio cholerae O1 are predicted to encode the enzymes required for the biosynthesis of perosamine, which constitutes the backbone structure of the O-antigen of the lipopolysaccharide. Based on homology to known proteins/protein families, the following functions are predicted: RfbA, phosphomannose isomerase-guanosine diphosphomannose pyrophosphorylase; RfbB, phosphomanno-mutase; RfbD, oxido reductase and RfbE, perosamine synthetase (amino-transferase). Thus, perosamine is synthesized from fructose 6-phosphate via the intermediates mannose 6-phosphate by RfbA, to mannose 1-phosphate by RfbB, to GDP-mannose by RfbA, to GDP-4-keto-6-dideoxymannose by RfbD and to GDP-perosamine by RfbE. This final product would then serve as the substrate for the addition of the tetronate, which could then be polymerized into the O-antigen for transfer to the lipid A plus core oligosaccharide and export to the cell surface. The organization of these genes are such that one would expect them to be translationally coupled as part of the rfb operon. However, the absence of readily detectable promoter sequences suggests low levels of transcription, in line with other studies. The nucleotide sequence of these genes is absolutely conserved in the two isolates 569B (classical...

‣ Comparison of the promoter proximal regions of the toxin-co-regulated tcp gene cluster in classical and El Tor strains of Vibrio cholerae O1

Ogierman, M.; Voss, E.; Meaney, C.; Faast, R.; Attridge, S.; Manning, P.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Publicado em //1996 Português
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A physical map has been constructed of the 5-kb XbaI fragment encoding the promoter proximal of region the tcp gene cluster encoding the toxin-coregulated pilus (TCP) of Vibrio cholerae. This fragment contains the major regulatory regions for TCP. Comparison of the nucleotide (nt) sequences from strains of the classical and El Tor biotypes demonstrates that the regions are essentially identical, with several notable exceptions. The intergenic regions, between tcpI and tcpP, and between tcpH and tcpA, show significant sequence divergence which may account for the biotype-related differences in TCP, since this is the location of the major promoter sequences. The C-terminal coding regions of the major pilin subunit, TcpA, also differ. Southern hybridization analyses suggest that the tcpA nt sequence is conserved within a biotype, and Western blot analysis suggests that the two forms of TcpA are antigenically different, but related. Besides tcpA, tcpB, tcpH and tcpI, the genes encoding two additional proteins, TcpP and TcpQ, but not previously defined, were also identified. TcpH and TcpI have been previously suggested to be regulatory proteins but homology data imply that TcpI is a methyl-accepting chemotaxis protein (MCP), as recently reported [Harkey et al....

‣ Comparative toxicity and virulence of Escherichia coli clones expressing variant and chimeric Shiga-like toxin type II operons

Paton, A.; Bourne, A.; Manning, P.; Paton, J.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em //1995 Português
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Shiga-like toxin (SLT)-producing strains of Escherichia coli are known to cause diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome in humans. The SLTs, particularly those related to type II (SLT-II), are a diverse family of toxins which may have differing in vitro or in vivo properties. To examine the impact of naturally occurring SLT-II sequence variation on the capacity of a given E. coli strain to cause disease, operons encoding four different SLT-II-related toxins, designated SLT-II/O111, SLT-II/OX3a, SLT-II/OX3b, and SLTII/ O48, were cloned in the same orientation in pBluescript. French pressure cell lysates of E. coli DH5a derivatives carrying these plasmids differed markedly in cytotoxicity for Vero cells, with 50% cytotoxic doses ranging from 20 to 328,000/ml. The strains also differed in oral virulence for streptomycin-treated mice, as judged by survival rate and/or median survival time, but virulence did not necessarily correlate with in vitro cytotoxicity. The SLT-II type associated with the lowest oral virulence was SLT-II/O111. Both the overall survival rate and the median survival time of mice challenged with clones producing this toxin were significantly greater than that for mice challenged with a clone producing the closely related SLT-II/OX3a. Experiments with clones carrying chimeric O111/OX3a SLT-II operons indicated that the reduced virulence was associated with an Arg-1763Gly substitution in the mature A subunit. Clones producing SLT-II/O48 and SLT-II/OX3b had similarly high cytotoxicities for Vero cells...

‣ The Shigella flexneri bacteriophage Sf6 tailspike protein (TSP)/endorhamnosidase is related to the bacteriophage P22 TSP and has a motif common to exo- and endoglycanases, and C-5 epimerases

Chua, J.; Manning, P.; Morona, R.
Fonte: SOC GENERAL MICROBIOLOGY Publicador: SOC GENERAL MICROBIOLOGY
Tipo: Artigo de Revista Científica
Publicado em //1999 Português
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The temperate bacteriophage Sf6 infects Shigella flexneri strains of serotype X or Y, converting them into serotypes 3a or 3b, respectively. The tailspike protein (TSP) of Sf6 possesses endo-1,3-alpha-L-rhamnosidase (endorhamnosidase) activity which results in cleavage of the lipopolysaccharide O-antigen receptor during the adsorption of the phage to the cell surface. When used in Southern hybridization, a P22 gene 9 (encoding P22 TSP) DNA probe hybridized with restriction fragment Pstl-7 of Sf6. DNA sequencing and analysis of Pstl-7 and the adjacent Pstl-8 fragment revealed an open reading frame (ORF1) of 1872 bp (624 amino acids) bearing amino acid sequence homology to the bacteriophage P22 TSP N-terminal head-binding domain. High conservation of key residues was suggestive of similar secondary and tertiary N-terminal protein structure and a similar function of the Sf6 TSP in this region. In addition, an amino acid sequence motif (DFGX3DGX6AX3A) was identified between residues 164 and 184 which was also found to exist in various prokaryotic and eukaryotic exo-/endoglycanases, C-5 epimerases and bacteriophage proteins. Expression of ORF1 from a T7 promoter produced a 67 kDa protein (detected by L-[35S]methionine labelling and SDS-PAGE). Assay of heat-treated cytoplasmic extracts containing the ORF1-encoded protein by incubation with whole Sh. flexneri Y cells demonstrated that O-antigen hydrolysis activity was present; ORF1 therefore encodes Sf6 TSP. Sf6 TSP exhibited specific and preferential activity for long-chain Sh. flexneri serotype X or Y O-antigen...

‣ Comparative and functional analyses of LYL1 loci establish marsupial sequences as a model for phylogenetic footprinting

Chapman, M.; Charchar, F.; Kinston, S.; Bird, C.; Grafham, D.; Rogers, J.; Grutzner, F.; Graves, J.; Green, A.; Gottgens, B.
Fonte: Academic Press Inc Elsevier Science Publicador: Academic Press Inc Elsevier Science
Tipo: Artigo de Revista Científica
Publicado em //2003 Português
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Comparative genomic sequence analysis is a powerful technique for identifying regulatory regions in genomic DNA. However, its utility largely depends on the evolutionary distances between the species involved. Here we describe the screening of a genomic BAC library from the stripe-faced dunnart, Sminthopsis macroura, formerly known as the narrow-footed marsupial mouse. We isolated a clone containing the LYL1 locus, completely sequenced the 60.6-kb insert, and compared it with orthologous human and mouse sequences. Noncoding homology was substantially reduced in the human/dunnart analysis compared with human/mouse, yet we could readily identify all promoters and exons. Human/mouse/dunnart alignments of the LYL1 candidate promoter allowed us to identify putative transcription factor binding sites, revealing a pattern highly reminiscent of critical regulatory regions of the LYL1 paralogue, SCL. This newly identified LYL1 promoter showed strong activity in myeloid progenitor cells and was bound in vivo by Fli1, Elf1, and Gata2-transcription factors all previously shown to bind to the SCL stem cell enhancer. This study represents the first large-scale comparative analysis involving marsupial genomic sequence and demonstrates that such comparisons provide a powerful approach to characterizing mammalian regulatory elements.; Michael A. Chapman...

‣ Ty-1 copia retrotransposon-based SSAP marker development in Cashew (Anacardium occidentale L.)

Syed, N.; Sureshsundar, S.; Wilkinson, M.; Bhau, B.; Cavalcanti, J.; Flavell, A.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2005 Português
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The most popular retrotransposon-based molecular marker system in use at the present time is the sequence-specific amplification polymorphism (SSAP) system . This system exploits the insertional polymorphism of long terminal repeat (LTR) retrotransposons around the genome. Because the LTR sequence is used to design primers for this method, its successful application requires sequence information from the terminal region of the mobile elements . In this study, two LTR sequences were isolated from the cashew genome and used successfully to develop SSAP marker systems. These were shown to have higher levels of polymorphism than amplified fragment length polymorphic markers for this species.; N. H. Syed, S. Sureshsundar, M. J. Wilkinson, B. S. Bhau, J. J. V. Cavalcanti, A. J. Flavell

‣ SnTox3 Acts in Effector Triggered Susceptibility to Induce Disease on Wheat Carrying the Snn3 Gene

Liu, Zhaohui; Faris, Justin D.; Oliver, Richard P.; Tan, Kar-Chun; Solomon, Peter S.; McDonald, Megan C.; McDonald, Bruce A.; Nunez, Alberto; Lu, Shunwen; Rasmussen, Jack B.; Friesen, Timothy L.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
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The necrotrophic fungus Stagonospora nodorum produces multiple proteinaceous host-selective toxins (HSTs) which act in effector triggered susceptibility. Here, we report the molecular cloning and functional characterization of the SnTox3-encoding gene, designated SnTox3, as well as the initial characterization of the SnTox3 protein. SnTox3 is a 693 bp intron-free gene with little obvious homology to other known genes. The predicted immature SnTox3 protein is 25.8 kDa in size. A 20 amino acid signal sequence as well as a possible pro sequence are predicted. Six cysteine residues are predicted to form disulfide bonds and are shown to be important for SnTox3 activity. Using heterologous expression in Pichia pastoris and transformation into an avirulent S. nodorum isolate, we show that SnTox3 encodes the SnTox3 protein and that SnTox3 interacts with the wheat susceptibility gene Snn3. In addition, the avirulent S. nodorum isolate transformed with SnTox3 was virulent on host lines expressing the Snn3 gene. SnTox3-disrupted mutants were deficient in the production of SnTox3 and avirulent on the Snn3 differential wheat line BG220. An analysis of genetic diversity revealed that SnTox3 is present in 60.1% of a worldwide collection of 923 isolates and occurs as eleven nucleotide haplotypes resulting in four amino acid haplotypes. The cloning of SnTox3 provides a fundamental tool for the investigation of the S. nodorum-wheat interaction...

‣ Analysis of the 5' portion of the type 19A capsule locus identifies two classes of cpsC, cpsD, and cpsE genes in Streptococcus pneumoniae

Morona, J.; Morona, R.; Paton, J.
Fonte: AMER SOC MICROBIOLOGY Publicador: AMER SOC MICROBIOLOGY
Tipo: Artigo de Revista Científica
Publicado em //1999 Português
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Analysis of the sequence data obtained from the 5' portion of the Streptococcus pneumoniae type 19A capsular polysaccharide biosynthesis locus (cps19a) revealed that the first seven genes are homologous to the first seven genes in the type 19F (cps19f) locus. The former genes were designated cps19aA to -G and were 70 to 90% identical to their cps19f counterparts. Southern hybridization analysis of the cps loci from various S. pneumoniae serotypes with probes specific for the cps19aC, cps19aD, and cps19aE genes indicated a hybridization pattern complementary to that previously reported for cps19fC, cps19fD, and cps19fE. That is, all serotypes tested contained high-stringency homologues of either the cps19aC to -E genes or the cps19fC to -E genes, but not both. On this basis S. pneumoniae cps loci can be divided into two distinct classes. Long-range PCR was used to amplify the cps regions between cpsB and aliA from a variety of pneumococcal serotypes. Direct sequencing of the 5' end of these PCR products, and phylogenetic analysis of the sequence data, confirmed the presence of the two distinct classes of cpsC. Whereas members within one class are greater than 95% identical to each other, the DNA sequence identity between the two classes is only approximately 70%.

‣ The X-linked gene G4.5 is responsible for different infantile dilated cardiomyopathies

D'Adamo, P.; Fassone, L.; Gedeon, A.; Janssen, E.; Bione, S.; Bolhuis, P.; Barth, P.; Wilson, M.; Haan, E.; Orstavik, H.; Patton, M.; Green, A.; Zammarchi, E.; Donati, M.; Toniolo, D.
Fonte: UNIV CHICAGO PRESS Publicador: UNIV CHICAGO PRESS
Tipo: Artigo de Revista Científica
Publicado em //1997 Português
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Barth syndrome (BTHS) is an X-linked disorder characterized clinically by the associated features of cardiac and skeletal myopathy, short stature, and neutropenia. The clinical manifestations of the disease are, in general, quite variable, but cardiac failure as a consequence of cardiac dilatation and hypertrophy is a constant finding and is the most common cause of death in the first months of life. X-linked cardiomyopathies with clinical manifestations similar to BTHS have been reported, and it has been proposed that they may be allelic. We have recently identified the gene responsible for BTHS, in one of the Xq28 genes, G4.5. In this paper we report the sequence analysis of 11 additional familial cases: 8 were diagnosed as possibly affected with BTHS, and 3 were affected with X-linked dilated cardiomyopathies. Mutations in the G4.5 gene were found in nine of the patients analyzed. The molecular studies have linked together what were formerly considered different conditions and have shown that the G4.5 gene is responsible for BTHS (OMIM 302060), X-linked endocardial fibroelastosis (OMIM 305300), and severe X-linked cardiomyopathy (OMIM 300069). Our results also suggest that very severe phenotypes may be associated with null mutations in the gene...

‣ Formation of sheared G:A base pairs in an RNA duplex modelled after ribozymes, as revealed by NMR.

Katahira, M; Kanagawa, M; Sato, H; Uesugi, S; Fujii, S; Kohno, T; Maeda, T
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 25/07/1994 Português
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The thermal stability and structure of an RNA duplex, r(GGACGAGUCC)2, the base sequence of which was modelled after both a hammerhead ribozyme and a lead ribozyme, were studied by CD and NMR. We previously demonstrated that the corresponding DNA duplex, d(GGACGAGTCC)2, formed unique 'sheared' G:A base pairs, where an amino proton, instead of an imino proton, of G is involved in the hydrogen bonding, and G and A bases are arranged 'side by side' instead of 'head to head' (Nucleic Acids Res. (1993) 21, 5418-5424). CD melting profiles showed that the RNA duplex is thermally more stable than the corresponding DNA duplex. NMR studies revealed that sheared G:A base pairs are formed in the RNA duplex, too, although the overall structure of the RNA is the A form, which differs from the B form taken on by the corresponding DNA. A model building study confirmed that sheared G:A base pairs can be accommodated in the double helical structure of the A form. A difference between the RNA and DNA duplexes in the stacking interaction involving G:A mismatch bases is also suggested. The demonstration that sheared G:A base pairs can be formed not only in DNA but also in RNA suggests that this base pairing plays an important role regarding the RNA structure.

‣ The genome sequence of the plant pathogen Xylella fastidiosa: The Xylella fastidiosa consortium of the organization for nucleotide sequencing and analysis, Sao Paulo, Brazil

Simpson, A. J G; Reinach, F. C.; Arruda, P.; Abreu, F. A.; Acencio, M.; Alvarenga, R.; Alves, L. M C; Araya, J. E.; Baia, G. S.; Baptista, C. S.; Barros, M. H.; Bonaccorsi, E. D.; Bordin, S.; Bové, J. M.; Briones, M. R S; Bueno, M. R P; Camargo, A. A.; C
Fonte: Macmillan Publishers Ltd Publicador: Macmillan Publishers Ltd
Tipo: Artigo de Revista Científica Formato: 151-157
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Xylella fastidiosa is a fastidious, xylem-limited bacterium that causes a range of economically important plant diseases. Here we report the complete genome sequence of X. fastidiosa clone 9a5c, which causes citrus variegated chlorosis - a serious disease of orange trees. The genome comprises a 52.7% GC-rich 2,679,305-base-pair (bp) circular chromosome and 'two plasmids of 51,158 bp and 1,285 bp. We can assign putative functions to47% of the 2,904 predicted coding regions. Efficient metabolic functions are predicted, with sugars as the principal energy and carbon source, supporting existence in the nutrient-poor xylem sap. The mechanisms associated with pathogenicity and virulence involve toxins, antibiotics and ion sequestration systems, as well as bacterium-bacterium and bacterium-host interactions mediated by a range of proteins. Orthologues of some of these proteins have only been identified in animal and human pathogens; their presence in X. fastidiosa indicates that the molecular basis for bacterial pathogenicity is both conserved and independent of host. At least 83 genes are bacteriophage-derived and include virulence-associated genes from other bacteria, providing direct evidence of phage-mediated horizontal gene transfer.