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Applied and Environmental Microbiology, August 2004, p. 4672-4680, Vol. 70, No. 8
0099-2240/04/$08.00+0 DOI: 10.1128/AEM.70.8.4672-4680.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
Jean-Marc Berjeaud,1 Didier Marion,2 Christian Lacombe,1 and Jacques Frère1*
Institut de Biologie Moléculaire et d'Ingénierie Génétique, Equipe de Microbiologie Fondamentale et Appliquée, UMR CNRS 6008, Université de Poitiers, 86022 Poitiers Cedex,1 Unité de Biochimie et Technologie des Protéines, INRA, 44316 Nantes Cedex 03, France2
Received 5 January 2004/ Accepted 27 April 2004
Mesentericin Y105 is a 37-residue bacteriocin produced by Leuconostoc mesenteroides Y105 that displays antagonistic activity against gram-positive bacteria such as Enterococcus faecalis and Listeria monocytogenes. It is closely related to leucocin A, an antimicrobial peptide containing ß-sheet and
-helical structures. To analyze structure-function relationships and the mode of action of this bacteriocin, we generated a collection of mesentericin derivatives. Mutations were obtained mostly by PCR random mutagenesis, and the peptides were produced by an original system of heterologous expression recently described (D. Morisset and J. Frère, Biochimie 84:569-576, 2002). Ten derivatives were obtained displaying modifications at eight different positions in the mesentericin Y105 sequence. Purified peptides were incorporated into lysophosphatidylcholine micelles and analyzed by circular dichroism. The
-helical contents of these peptides were compared and related to their respective bactericidal activities. Moreover, studies of the intrinsic fluorescence of tryptophan residues naturally occurring at positions 18 and 37 revealed information about insertion of the peptides in micelles. A model for the mode of action of mesentericin Y105 and related bacteriocins is proposed.
Present address: Département de Biochimie et de Microbiologie, Université Laval, Québec, Québec, Canada G1K 7P4.
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