Stimulation of PgdA‐dependent peptidoglycan N‐deacetylation by GpsB‐PBP A1 in Listeria monocytogenes

Abstract

Listeria monocytogenes and other pathogenic bacteria modify their peptidoglycan to protect it against enzymatic attack through the host innate immune system, such as the cell wall hydrolase lysozyme. During our studies on GpsB, a late cell division protein that controls activity of the bi-functional penicillin binding protein PBP A1, we discovered that GpsB influences lysozyme resistance of L. monocytogenes as mutant strains lacking gpsB showed an increased lysozyme resistance. Deletion of pbpA1 corrected this effect, demonstrating that PBP A1 is also involved in this. Susceptibility to lysozyme mainly depends on two peptidoglycan modifying enzymes: The peptidoglycan N-deacetylase PgdA and the peptidoglycan O-acetyltransferase OatA. Genetic and biochemical experiments consistently demonstrated that the increased lysozyme resistance of the ΔgpsB mutant was PgdA-dependent and OatA-independent. Protein-protein interaction studies supported the idea that GpsB, PBP A1 and PgdA form a complex in L. monocytogenes and identified the regions in PBP A1 and PgdA required for complex formation. These results establish a physiological connection between GpsB, PBP A1 and the peptidoglycan modifying enzyme PgdA. To our knowledge, this is the first reported link between a GpsB-like cell division protein and factors important for escape from the host immune system.

The cell cycle regulator GpsB functions as cytosolic adaptor for multiple cell wall enzymes

“…Deletion of gpsB alone in Listeria monocytogenes caused marked growth and division defects at 37 °C and was lethal at 42 °C 19 . Moreover, gpsB deletion in L. monocytogenes also resulted in enhanced susceptibility to β-lactam 19 and fosfomycin 20 antibiotics, reduced virulence in an insect infection model 19 , and caused alterations to PG structure 21 . Mutations in gpsB that affected binding to the PG synthase PBPA1 also showed a lethal phenotype in L. monocytogenes at 42 °C 19 .…”

EslB is required for cell wall biosynthesis and modification inListeria monocytogenes

“…Since we saw a slight increase in the deacetylation of GlcNAc residues in the eslB mutant strain, our results indicate that the lysozyme sensitivity phenotype of the eslB deletion strain is independent of PgdA and that this enzyme functions properly in the mutant strain. A second enzyme required for lysozyme resistance in L. monocytogenes is OatA, which transfers O-acetyl groups to MurNAc (10,34,35). Using a colorimetric O-acetylation assay, we were able to show that PG isolated from the eslB mutant is less O-acetylated and we assume that this reduction in O-acetylation contributes to the lysozyme sensitivity of strain 10403SDeslB.…”

The Basic-Region Helix-Loop-Helix Transcription Factor DevR Significantly Affects Polysaccharide Metabolism in Aspergillus oryzae

“…Cell wall metabolism and cell wall modification are very important processes that microorganisms use to adjust to various environmental conditions. The AO090003001241 protein-encoding sequence was also similar to that of PgdA, which was shown to participate in cell wall modification, and its deletion mutant was sensitive to lysozyme treatment (28,29). However, the expression of the chitin synthase gene (AO090005000353) was significantly increased in the OE-devR strain.…”