Enzymology of the bacterial cell wall recycling

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An intrinsic consequence of bacterial growth is the breakdown of the expanding cell wall and the release of peptidoglycan turnover products that can be reutilized (recycled). Little is known about cell wall recycling except for the Gram-negative bacterium Escherichia coli. However, Gram-positive bacteria generate peptidoglycan turnover products different from those of Gram-negative bacteria and recycling very likely proceeds through different pathways. Knowing the differences and the enzymology behind these processes would allow new selective strategies for antibiotic treatment of Gram-positive and Gram-negative bacteria. We want to study peptidoglycan recycling in the Gram-positive model organism Bacillus subtilis. The enzymology of two classes of enzymes involved in peptidoglycan recycling will be studied in detail. First, we will be studying the N-acetylglucosaminidases to establish the mechanistical consequences of these enzymes differing in size, domain structure and localization as well as acting on different substrates in Gram-positive and Gram-negative bacteria. Second, we will be studying the lactyl etherases which cleave the D-lactyl ether substituent of the cell wall sugar N-acetylmuramic acid and which were identified in our group recently. They represent a novel class of etherases that presumably catalyze a ß-elimination (lyase-typ) reaction.