Document Detail

Analysis of proline reduction in the nosocomial pathogen Clostridium difficile.
MedLine Citation:
PMID:  17041035     Owner:  NLM     Status:  MEDLINE    
Clostridium difficile, a proteolytic strict anaerobe, has emerged as a clinically significant nosocomial pathogen in recent years. Pathogenesis is due to the production of lethal toxins, A and B, members of the large clostridial cytotoxin family. Although it has been established that alterations in the amino acid content of the growth medium affect toxin production, the molecular mechanism for this observed effect is not yet known. Since there is a paucity of information on the amino acid fermentation pathways used by this pathogen, we investigated whether Stickland reactions might be at the heart of its bioenergetic pathways. Growth of C. difficile on Stickland pairs yielded large increases in cell density in a limiting basal medium, demonstrating that these reactions are tied to ATP production. Selenium supplementation was required for this increase in cell yield. Analysis of genome sequence data reveals genes encoding the protein components of two key selenoenzyme reductases, glycine reductase and d-proline reductase (PR). These selenoenzymes were expressed upon the addition of the corresponding Stickland acceptor (glycine, proline, or hydroxyproline). Purification of the selenoenzyme d-proline reductase revealed a mixed complex of PrdA and PrdB (SeCys-containing) proteins. PR utilized only d-proline but not l-hydroxyproline, even in the presence of an expressed and purified proline racemase. PR was found to be independent of divalent cations, and zinc was a potent inhibitor of PR. These results show that Stickland reactions are key to the growth of C. difficile and that the mechanism of PR may differ significantly from that of previously studied PR from nonpathogenic species.
Sarah Jackson; Mary Calos; Andrew Myers; William T Self
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Publication Detail:
Type:  Journal Article     Date:  2006-10-13
Journal Detail:
Title:  Journal of bacteriology     Volume:  188     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  2006 Dec 
Date Detail:
Created Date:  2006-12-05     Completed Date:  2007-01-16     Revised Date:  2013-06-07    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  8487-95     Citation Subset:  IM    
Department of Molecular Biology and Microbiology, Burnett College of Biomedical Science, University of Central Florida, Orlando, FL 32816-2364, USA.
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MeSH Terms
Amino Acid Isomerases / metabolism
Amino Acid Oxidoreductases / genetics,  isolation & purification,  metabolism*
Clostridium difficile / genetics,  growth & development,  metabolism*
Cross Infection / microbiology*
Culture Media
Enterocolitis, Pseudomembranous / microbiology*
Glycine / metabolism
Hydroxyproline / metabolism
Multienzyme Complexes / genetics,  metabolism
Proline / metabolism*
Selenium / metabolism
Reg. No./Substance:
0/Culture Media; 0/Multienzyme Complexes; 147-85-3/Proline; 51-35-4/Hydroxyproline; 56-40-6/Glycine; 7782-49-2/Selenium; EC reductase (dithiol); EC 1.4.-/Amino Acid Oxidoreductases; EC 1.4.1.-/glycine reductase; EC 5.1.1.-/Amino Acid Isomerases; EC racemase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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