4g76

Publication Abstract from PubMed

Colicin M (ColM) is the only enzymatic colicin reported to date that inhibits cell wall peptidoglycan biosynthesis. It catalyzes the specific degradation of the lipid intermediates involved in this pathway, thereby provoking lysis of susceptible Escherichia coli cells. A gene encoding a homologue of ColM was detected within the exoU-containing genomic island A carried by certain pathogenic Pseudomonas aeruginosa strains. This bacteriocin (pyocin) that we have named PaeM was crystallized and its structure with and without an Mg(2+) ion bound was solved. In parallel, site-directed mutagenesis of conserved PaeM residues from the C-terminal domain was performed, confirming their essentiality for the protein activity both in vitro (lipid II-degrading activity) and in vivo (cytotoxicity against a susceptible P. aeruginosa strain). Although PaeM is structurally similar to ColM, the conformation of their active sites differs radically: in PaeM, residues essential for enzymatic activity and cytotoxicity converge towards a same pocket while in ColM, they are spread along a particularly elongated active site. We have also isolated a minimal domain corresponding to the C-terminal half of the PaeM protein and exhibiting a 70-fold higher enzymatic activity as compared to the full-length protein. This isolated domain of the PaeM bacteriocin was further shown to kill E. coli cells when addressed to the periplasm of these bacteria.

Functional and structural characterization of PaeM, a colicin M-like bacteriocin produced by Pseudomonas aeruginosa.,Barreteau H, Tiouajni M, Graille M, Josseaume N, Bouhss A, Patin D, Blanot D, Fourgeaud M, Mainardi JL, Arthur M, van Tilbeurgh H, Mengin-Lecreulx D, Touze T J Biol Chem. 2012 Sep 12. PMID:22977250^[1]

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