Insight into Invertebrate Defensin Mechanism of Action OYSTER DEFENSINS INHIBIT PEPTIDOGLYCAN BIOSYNTHESIS BY BINDING TO LIPID II
|Author(s)||Schmitt Paulina1, 2, Wilmes Miriam3, Pugniere Martine7, Aumelas Andre4, 5, 6, Bachere Evelyne1, 2, Sahl Hans-Georg3, Schneider Tanja3, Destoumieux-Garzon Delphine1, 2|
|Affiliation(s)||1 : Univ Montpellier 2, CNRS, UMR 5119, Lab Ecosyst Lagunaires, F-34095 Montpellier, France.
2 : Univ Montpellier 2, IFREMER, UMR 5119, Lab Ecosyst Lagunaires,IRD, F-34095 Montpellier, France.
3 : Univ Bonn, Inst Med Microbiol Immunol & Parasitol, Pharmaceut Microbiol Sect, D-53105 Bonn, Germany.
4 : CNRS, UMR 5048, INSERM, U554, F-34090 Montpellier, France.
5 : Univ Montpellier 1, Ctr Biochim Struct, F-34090 Montpellier, France.
6 : Univ Montpellier 2, Ctr Biochim Struct, F-34090 Montpellier, France.
7 : Ctr Etud Agents Pathogenes & Biotechnol Sante, CNRS, UMR 5236, Inst Biol, F-34965 Montpellier, France.
|Source||Journal Of Biological Chemistry (0021-9258) (Amer Soc Biochemistry Molecular Biology Inc), 2010-09 , Vol. 285 , N. 38 , P. 29208-29216|
|WOS© Times Cited||96|
|Abstract||Three oyster defensin variants (Cg-Defh1, Cg-Defh2, and Cg-Defm) were produced as recombinant peptides and characterized in terms of activities and mechanism of action. In agreement with their spectrum of activity almost specifically directed against Gram-positive bacteria, oyster defensins were shown here to be specific inhibitors of a bacterial biosynthesis pathway rather than mere membrane-active agents. Indeed, at lethal concentrations, the three defensins did not compromise Staphylococcus aureus membrane integrity but inhibited the cell wall biosynthesis as indicated by the accumulation of the UDP-N-acetylmuramyl-pentapeptide cell wall precursor. In addition, a combination of antagonization assays, thin layer chromatography, and surface plasmon resonance measurements showed that oyster defensins bind almost irreversibly to the lipid II peptidoglycan precursor, thereby inhibiting the cell wall biosynthesis. To our knowledge, this is the first detailed analysis of the mechanism of action of antibacterial defensins produced by invertebrates. Interestingly, the three defensins, which were chosen as representative of the oyster defensin molecular diversity, bound differentially to lipid II. This correlated with their differential antibacterial activities. From our experimental data and the analysis of oyster defensin sequence diversity, we propose that oyster defensin activity results from selective forces that have conserved residues involved in lipid II binding and diversified residues at the surface of oyster defensins that could improve electrostatic interactions with the bacterial membranes.|