The large mechanosensitive channel MscL determines bacterial susceptibility to the bacteriocin sublancin 168.
Bacillus subtilis strain 168 produces the extremely stable and broad-spectrum lantibiotic sublancin 168. Known sublancin 168-susceptible organisms include important pathogens, such as Staphylococcus aureus. Nevertheless, since its discovery, the mode of action of sublancin 168 has remained elusive. The present studies were, therefore, aimed at the identification of cellular determinants for bacterial susceptibility toward sublancin 168. Growth inhibition and competition assays on plates and in liquid cultures revealed that sublancin 168-mediated growth inhibition of susceptible B. subtilis and S. aureus cells is affected by the NaCl concentration in the growth medium. Added NaCl did not influence the production, activity, or stability of sublancin 168 but, instead, lowered the susceptibility of sensitive cells toward this lantibiotic. Importantly, the susceptibility of B. subtilis and S. aureus cells toward sublancin 168 was shown to depend on the presence of the large mechanosensitive channel of conductance MscL. In contrast, MscL was not involved in susceptibility toward the bacteriocin nisin or Pep5. Taken together, our unprecedented results demonstrate that MscL is a critical and specific determinant in bacterial sublancin 168 susceptibility that may serve either as a direct target for this lantibiotic or as a gate of entry to the cytoplasm.
Kouwen
Thijs R H M
TR
Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, Hanzeplein 1, P.O. Box 30001, 9700 RB Groningen, The Netherlands.
Trip
Erik N
EN
Denham
Emma L
EL
Sibbald
Mark J J B
MJ
Dubois
Jean-Yves F
JY
van Dijl
Jan Maarten
JM
D001412:Bacillus subtilis / Q000187:drug effects*; D001426:Bacterial Proteins / Q000502:physiology*; D001430:Bacteriocins / Q000494:pharmacology*; D006020:Glycopeptides; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D008826:Microbial Sensitivity Tests; D010455:Peptides / Q000494:pharmacology*; D012965:Sodium Chloride / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects*
D001426:Bacterial Proteins; D001430:Bacteriocins; D006020:Glycopeptides; D010455:Peptides; C114602:sublancin 168; D012965:Sodium Chloride