Characterization of AmiBA2446, a novel bacteriolytic enzyme active against Bacillus species

Appl Environ Microbiol. 2013 Oct;79(19):5899-906. doi: 10.1128/AEM.02235-13. Epub 2013 Jul 19.

Abstract

There continues to be a need for developing efficient and environmentally friendly treatments for Bacillus anthracis, the causative agent of anthrax. One emerging approach for inactivation of vegetative B. anthracis is the use of bacteriophage endolysins or lytic enzymes encoded by bacterial genomes (autolysins) with highly evolved specificity toward bacterium-specific peptidoglycan cell walls. In this work, we performed in silico analysis of the genome of Bacillus anthracis strain Ames, using a consensus binding domain amino acid sequence as a probe, and identified a novel lytic enzyme that we termed AmiBA2446. This enzyme exists as a homodimer, as determined by size exclusion studies. It possesses N-acetylmuramoyl-l-alanine amidase activity, as determined from liquid chromatography-mass spectrometry (LC-MS) analysis of muropeptides released due to the enzymatic digestion of peptidoglycan. Phylogenetic analysis suggested that AmiBA2446 was an autolysin of bacterial origin. We characterized the effects of enzyme concentration and phase of bacterial growth on bactericidal activity and observed close to a 5-log reduction in the viability of cells of Bacillus cereus 4342, a surrogate for B. anthracis. We further tested the bactericidal activity of AmiBA2446 against various Bacillus species and demonstrated significant activity against B. anthracis and B. cereus strains. We also demonstrated activity against B. anthracis spores after pretreatment with germinants. AmiBA2446 enzyme was also stable in solution, retaining its activity after 4 months of storage at room temperature.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / metabolism*
  • Bacillus anthracis / drug effects*
  • Bacillus anthracis / enzymology*
  • Bacillus anthracis / genetics
  • Bacillus cereus / drug effects
  • Bacteriolysis*
  • Chromatography, Liquid
  • Cluster Analysis
  • Hydrolysis
  • Mass Spectrometry
  • Microbial Viability*
  • N-Acetylmuramoyl-L-alanine Amidase / genetics
  • N-Acetylmuramoyl-L-alanine Amidase / metabolism*
  • Peptidoglycan / metabolism
  • Phylogeny
  • Sequence Homology, Amino Acid

Substances

  • Anti-Bacterial Agents
  • Peptidoglycan
  • N-Acetylmuramoyl-L-alanine Amidase