LytA, major autolysin of Streptococcus pneumoniae, requires access to nascent peptidoglycan

J Biol Chem. 2012 Mar 30;287(14):11018-29. doi: 10.1074/jbc.M111.318584. Epub 2012 Feb 9.

Abstract

The pneumococcal autolysin LytA is a virulence factor involved in autolysis as well as in fratricidal- and penicillin-induced lysis. In this study, we used biochemical and molecular biological approaches to elucidate which factors control the cytoplasmic translocation and lytic activation of LytA. We show that LytA is mainly localized intracellularly, as only a small fraction was found attached to the extracellular cell wall. By manipulating the extracellular concentration of LytA, we found that the cells were protected from lysis during exponential growth, but not in the stationary phase, and that a defined threshold concentration of extracellular LytA dictates the onset of autolysis. Stalling growth through nutrient depletion, or the specific arrest of cell wall synthesis, sensitized cells for LytA-mediated lysis. Inhibition of cell wall association via the choline binding domain of an exogenously added enzymatically inactive form of LytA revealed a potential substrate for the amidase domain within the cell wall where the formation of nascent peptidoglycan occurs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacteriolysis* / drug effects
  • Cell Division / drug effects
  • Cell Proliferation / drug effects
  • Cytoplasm / drug effects
  • Cytoplasm / metabolism
  • Deoxycholic Acid / pharmacology
  • Detergents / pharmacology
  • Extracellular Space / drug effects
  • Extracellular Space / metabolism
  • N-Acetylmuramoyl-L-alanine Amidase / chemistry
  • N-Acetylmuramoyl-L-alanine Amidase / genetics
  • N-Acetylmuramoyl-L-alanine Amidase / metabolism*
  • N-Acetylmuramoyl-L-alanine Amidase / pharmacology
  • Peptidoglycan / biosynthesis*
  • Peptidoglycan / metabolism*
  • Protein Sorting Signals
  • Protein Transport / drug effects
  • Streptococcus pneumoniae / cytology*
  • Streptococcus pneumoniae / drug effects
  • Streptococcus pneumoniae / enzymology*
  • Streptococcus pneumoniae / metabolism

Substances

  • Anti-Bacterial Agents
  • Detergents
  • Peptidoglycan
  • Protein Sorting Signals
  • Deoxycholic Acid
  • N-Acetylmuramoyl-L-alanine Amidase