Enzymology of the bacterial cell wall recycling

细菌生长的内在结果是扩展的细胞壁的分解和可以再利用（再循环）的肽聚糖周转产物的释放。除了革兰氏阴性细菌大肠杆菌外，对细胞壁回收知之甚少。然而，革兰氏阳性细菌产生的肽聚糖周转产物与革兰氏阴性细菌不同，并且回收很可能通过不同的途径进行。了解这些过程背后的差异和酶学将允许新的选择性策略用于革兰氏阳性和革兰氏阴性细菌的抗生素治疗。我们想研究革兰氏阳性模式生物枯草芽孢杆菌中的肽聚糖循环。参与肽聚糖再循环的两类酶的酶学将被详细研究。首先，我们将研究N-乙酰氨基葡萄糖苷酶，以确定这些酶在大小、结构域结构和定位上不同以及作用于革兰氏阳性和革兰氏阴性细菌中不同底物的机械后果。第二，我们将研究乳酰醚酶，它切割细胞壁糖N-乙酰胞壁酸的D-乳酰醚取代基，这是我们小组最近鉴定的。它们代表了一类新的醚酶，可能催化β-消除（裂解酶型）反应。

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.