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Structural and biochemical analyses of a Clostridium perfringens sortase D transpeptidase.

ABSTRACT: The assembly and anchorage of various pathogenic proteins on the surface of Gram-positive bacteria is mediated by the sortase family of enzymes. These cysteine transpeptidases catalyze a unique sorting signal motif located at the C-terminus of their target substrate and promote the covalent attachment of these proteins onto an amino nucleophile located on another protein or on the bacterial cell wall. Each of the six distinct classes of sortases displays a unique biological role, with sequential activation of multiple sortases often observed in many Gram-positive bacteria to decorate their peptidoglycans. Less is known about the members of the class D family of sortases (SrtD), but they have a suggested role in spore formation in an oxygen-limiting environment. Here, the crystal structure of the SrtD enzyme from Clostridium perfringens was determined at 1.99?Å resolution. Comparative analysis of the C. perfringens SrtD structure reveals the typical eight-stranded ?-barrel fold observed in all other known sortases, along with the conserved catalytic triad consisting of cysteine, histidine and arginine residues. Biochemical approaches further reveal the specifics of the SrtD catalytic activity in vitro, with a significant preference for the LPQTGS sorting motif. Additionally, the catalytic activity of SrtD is most efficient at 316?K and can be further improved in the presence of magnesium cations. Since C. perfringens spores are heat-resistant and lead to foodborne illnesses, characterization of the spore-promoting sortase SrtD may lead to the development of new antimicrobial agents.

SUBMITTER: Suryadinata R

PROVIDER: S-EPMC4498605 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Structural and biochemical analyses of a Clostridium perfringens sortase D transpeptidase.

Suryadinata Randy R Seabrook Shane A SA Adams Timothy E TE Nuttall Stewart D SD Peat Thomas S TS

Acta crystallographica. Section D, Biological crystallography 20150630 Pt 7

The assembly and anchorage of various pathogenic proteins on the surface of Gram-positive bacteria is mediated by the sortase family of enzymes. These cysteine transpeptidases catalyze a unique sorting signal motif located at the C-terminus of their target substrate and promote the covalent attachment of these proteins onto an amino nucleophile located on another protein or on the bacterial cell wall. Each of the six distinct classes of sortases displays a unique biological role, with sequential ...[more]

PMID: 26143922

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Project description:Clostridium perfringens is an anaerobic bacterium that causes numerous important human and animal diseases, primarily as a result of its ability to produce many different protein toxins. In chickens, C. perfringens causes necrotic enteritis, a disease of economic importance to the worldwide poultry industry. The secreted pore-forming toxin NetB is a key virulence factor in the pathogenesis of avian necrotic enteritis and is similar to alpha-hemolysin, a ?-barrel pore-forming toxin from Staphylococcus aureus. To address the molecular mechanisms underlying NetB-mediated tissue damage, we determined the crystal structure of the monomeric form of NetB to 1.8 Å. Structural comparisons with other members of the alpha-hemolysin family revealed significant differences in the conformation of the membrane binding domain. These data suggested that NetB may recognize different membrane receptors or use a different mechanism for membrane-protein interactions. Consistent with this idea, electrophysiological experiments with planar lipid bilayers revealed that NetB formed pores with much larger single-channel conductance than alpha-hemolysin. Channel conductance varied with phospholipid net charge. Furthermore, NetB differed in its ion selectivity, preferring cations over anions. Using hemolysis as a screen, we carried out a random-mutagenesis study that identified several residues that are critical for NetB-induced cell lysis. Mapping of these residues onto the crystal structure revealed that they were clustered in regions predicted to be required for oligomerization or membrane binding. Together these data provide an insight into the mechanism of NetB-mediated pore formation and will contribute to our understanding of the mode of action of this important toxin. IMPORTANCE Necrotic enteritis is an economically important disease of the worldwide poultry industry and is mediated by Clostridium perfringens strains that produce NetB, a ?-pore-forming toxin. We carried out structural and functional studies of NetB to provide a mechanistic insight into its mode of action and to assist in the development of a necrotic enteritis vaccine. We determined the structure of the monomeric form of NetB to 1.8 Å, used both site-directed and random mutagenesis to identify key residues that are required for its biological activity, and analyzed pore formation by NetB and its substitution-containing derivatives in planar lipid bilayers.

Project description:Purpose: RNA-Seq has become a powerful tool for investigating transcriptional profiles in gene expression analysis, which would help to reveal the molecular mechanism of Clostridium perfringens type C infecting the piglets. In this study, we analyzed miRNA profiles of the ileum of piglets caused by Clostridium perfringens type C. Methods: 30 normal 7-day-old piglets (Y x L), without infecting Clostridium perfringens type C, Escherichia coli and Salmonella, were selected as experimental subjects. 25 piglets were randomly selected as the experimental group, which were disposed once a day for 5 days. Each piglet was dosed with 1 ml of bouillon culture-medium inoculated Clostridium perfringens type C at 37℃ for 16h, which approximate to 1 x10e9 CFU per ml. Then, 5 piglets were randomly selected as the control group (IC), which were taken the equal volume medium for 5 days.Based on total diarrhea scores, 25 piglets were ranked from high to low. The top and last five piglet were considered as sensitive group (IS) and resistant group (IR), respectively. Finally, ileum were collected and sequenced for miRNA. Result: 53 differentially expressed miRNAs were found. KEGG pathway analysis for target genes revealed that these miRNAs were involved in ErbB signaling pathway, MAPK signaling pathway, Jak-STAT signaling pathway and Wnt signaling pathway. The expression correlation analysis between miRNAs and target genes revealed that the expression of miR-7134-5p had negative correlation with target NFATC4, miR-500 had negative correlation with target ELK1, HSPA2 and IL7R, and miR-92b-3p had negative correlation with target CLCF1 in ileum of IR vs IS group, suggesting that miR-7134-5p targeting to NFATC4, miR-500 targeting to ELK1, HSPA2 and IL7R, and miR-92b-3p targeting to CLCF1 were probably involved in piglet resisting C. perfringens type C. Conclusions: The results will provide value resources for better understanding of the genetic basis of C. perfringens type C resistance in piglet and lays a new foundation for identifying novel markers of C. perfringens type C resistance

Dataset Information

Structural and biochemical analyses of a Clostridium perfringens sortase D transpeptidase.

Publications

Structural and biochemical analyses of a Clostridium perfringens sortase D transpeptidase.

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