Peer-Reviewed Journal Details
Mandatory Fields
Rea, MC,Sit, CS,Clayton, E,O'Connor, PM,Whittal, RM,Zheng, J,Vederas, JC,Ross, RP,Hill, C
Proceedings of The National Academy of Sciences of The United States of America
Thuricin CD, a posttranslationally modified bacteriocin with a narrow spectrum of activity against Clostridium difficile
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two-component bacteriocin posttranslational modifications Clostridium difficile-associated disease peptide NMR BACILLUS-THURINGIENSIS ANTIMICROBIAL PEPTIDE ENTERIC DISEASE IDENTIFICATION PURIFICATION TRANSPORT SUBTILIS DIARRHEA IMMUNITY
The last decade has seen numerous outbreaks of Clostridium difficile-associated disease (CDAD), which presented significant challenges for healthcare facilities worldwide. We have identified and purified thuricin CD, a two-component antimicrobial that shows activity against C. difficile in the nanomolar range. Thuricin CD is produced by Bacillus thuringiensis DPC 6431, a bacterial strain isolated from a human fecal sample, and it consists of two distinct peptides, Trn-alpha and Trn-beta, that act synergistically to kill a wide range of clinical C. difficile isolates, including ribotypes commonly associated with CDAD (e. g., ribotype 027). However, this bacteriocin thuricin CD has little impact on most other genera, including many gastrointestinal commensals. Complete amino acid sequencing using infusion tandem mass spectrometry indicated that each peptide is posttranslationally modified at its respective 21st, 25th, and 28th residues. Solution NMR studies on [C-13, N-15] Trn-alpha and [C-13, N-15] Trn-beta were used to characterize these modifications. Analysis of multidimensional NOESY data shows that specific cysteines are linked to the alpha-carbons of the modified residues, forming three sulfur to alpha-carbon bridges. Complete sequencing of the thuricin CD gene cluster revealed genes capable of encoding two S'-adenosylmethionine proteins that are characteristically associated with unusual posttranslational modifications. Thuricin CD is a two-component antimicrobial peptide system with sulfur to alpha-carbon linkages, and it may have potential as a targeted therapy in the treatment of CDAD while also reducing collateral impact on the commensal flora.
DOI 10.1073/pnas.0913554107
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