Specific interaction of the unmodified bacteriocin Lactococcin 972 with the cell wall precursor lipid II.
Lactococcin 972 (Lcn972) is a nonlantibiotic bacteriocin that inhibits septum biosynthesis in Lactococcus lactis rather than forming pores in the cytoplasmic membrane. In this study, a deeper analysis of the molecular basis of the mode of action of Lcn972 was performed. Of several lipid cell wall precursors, only lipid II antagonized Lcn972 inhibitory activity in vivo. Likewise, Lcn972 only coprecipitated with lipid II micelles. This bacteriocin inhibited the in vitro polymerization of lipid II by the recombinant S. aureus PBP2 and the addition to lipid II of the first glycine catalyzed by FemX. These experiments demonstrate that Lcn972 specifically interacts with lipid II, the substrate of both enzymes. In the presence of Lcn972, nisin pore formation was partially hindered in whole cells. However, binding of Lcn972 to lipid II could not compete with nisin in lipid II-doped 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes, possibly indicating a distinct binding site. The existence of a putative cotarget for Lcn972 activity is discussed in the context of its narrow inhibitory spectrum and the localized action at the division septum. To our knowledge, this is the first unmodified bacteriocin that binds to the cell wall precursor lipid II.
Instituto de Productos Lácteos de Asturias, IPLA-CSIC, Carretera de Infiesto s/n Apdo. 85, 33300 Villaviciosa, Spain. bmf1@ipla.csic.es
Beatriz
B
Martínez
Tim
T
Böttiger
Tanja
T
Schneider
Ana
A
Rodríguez
Hans-Georg
HG
Sahl
Imke
I
Wiedemann
D001430:Bacteriocins / Q000302:isolation & purification / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002473:Cell Wall / Q000187:drug effects / Q000502:physiology*; D005452:Fluoresceins / Q000378:metabolism; D007700:Kinetics; D013294:Lactococcus lactis / Q000187:drug effects / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism
D001430:Bacteriocins; D005452:Fluoresceins; D008563:Membrane Lipids; C402706:lactococcin 972; C024098:6-carboxyfluorescein; D011188:Potassium