The mode of action of the lantibiotic lacticin 3147--a complex mechanism involving specific interaction of two peptides and the cell wall precursor lipid II.
Lacticin 3147 is a two-peptide lantibiotic produced by Lactococcus lactis in which both peptides, LtnA1 and LtnA2, interact synergistically to produce antibiotic activities in the nanomolar concentration range; the individual peptides possess marginal (LtnA1) or no activity (LtnA2). We analysed the molecular basis for the synergism and found the cell wall precursor lipid II to play a crucial role as a target molecule. Tryptophan fluorescence measurements identified LtnA1, which is structurally similar to the lantibiotic mersacidin, as the lipid II binding component. However, LtnA1 on its own was not able to substantially inhibit cell wall biosynthesis in vitro; for full inhibition, LtnA2 was necessary. Both peptides together caused rapid K(+) leakage from intact cells; in model membranes supplemented with lipid II, the formation of defined pores with a diameter of 0.6 nm was observed. We propose a mode of action model in which LtnA1 first interacts specifically with lipid II in the outer leaflet of the bacterial cytoplasmic membrane. The resulting lipid II:LtnA1 complex is then able to recruit LtnA2 which leads to a high-affinity, three-component complex and subsequently inhibition of cell wall biosynthesis combined with pore formation.
Wiedemann
Imke
I
Institute for Medical Microbiology, Immunology and Parasitolog, Pharmaceutical Microbiology Unit, University of Bonn, D-53115 Bonn, Germany. Imke.Wiedemann@ukb.uni-bonn.de
Böttiger
Tim
T
Bonelli
Raquel R
RR
Wiese
Andre
A
Hagge
Sven O
SO
Gutsmann
Thomas
T
Seydel
Ulrich
U
Deegan
Lucy
L
Hill
Colin
C
Ross
Paul
P
Sahl
Hans-Georg
HG
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001430:Bacteriocins / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects; D002473:Cell Wall / Q000187:drug effects* / Q000378:metabolism; D008081:Liposomes; D008826:Microbial Sensitivity Tests; D008837:Micrococcus / Q000187:drug effects / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013210:Staphylococcus / Q000187:drug effects / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism; D014538:Uridine Diphosphate N-Acetylmuramic Acid / Q000031:analogs & derivatives* / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D008081:Liposomes; D010455:Peptides; D014538:Uridine Diphosphate N-Acetylmuramic Acid; C069249:muramyl-NAc-(pentapeptide)pyrophosphoryl-undecaprenol; C082508:lacticin 481; D014364:Tryptophan; D011188:Potassium