Muropeptide Recycling Pathway & Beta Lactamase Induction

描述（由申请人提供）：令人惊讶的是，大肠杆菌每一代从其侧壁降解超过60%的蛋白（肽聚糖），并能够重新利用这些成分。这个过程被称为循环利用。本研究的目的是鉴定和表征大肠杆菌再利用细胞壁肽聚糖成分所使用的所有酶。回收涉及超过10种酶，这些酶似乎除了促进蛋白质成分的分解和再利用外没有其他目的。为了充分了解这一进程，仍有几个悬而未决的问题有待回答。在许多革兰氏阴性生物中，β -内酰胺酶的诱导需要循环途径，此外，我们最近观察到某些循环基因的突变会导致自聚集和生物膜的形成。因此，该途径对青霉素耐药性和生物膜形成的健康相关领域很感兴趣。目标1：确定在缺乏n -乙酰氨基葡萄糖激酶的情况下利用n -乙酰氨基葡萄糖胺的途径。我们已经实现了Aim 1的最初目标，即鉴定激酶基因并证明其在n -乙酰氨基葡萄糖再利用中的作用。目的2：确定大肠杆菌如何降解无氢n -乙酰氨基乙酸。我们最近的结果表明，一个激酶和醚酶可能参与其中。因此，我们目前的努力旨在净化这些活动，以确定负责这些活动的基因。目标3：确定β -内酰胺酶的真正诱导剂。目的4：确定抗原43的表达与鼠蛋白三肽循环的关系。抗原43引起自身聚集，促进生物膜的形成。小鼠肽连接酶（mpl）或小鼠肽酰胺酶A （mpaA）的缺失导致三肽和抗原43的产生，这表明可能参与了小鼠三肽l - α - γ -d -葡萄糖-中二氨基戊酸的积累。

DESCRIPTION (provided by applicant): Amazingly, Escherichia coli degrades over 60% of the murein (peptidoglycan) from its sidewalls each generation and is able to reutilize the components. This process is known as recycling. The goat of this research is to identify and characterize all the enzymes used by E. coli to reutilize cell wall peptidoglycan components. Recycling involves over 10 enzymes that appear to serve no other purpose than to facilitate breakdown and reutilization of murein components. Several outstanding questions remain to be answered in order to have a full understanding of the process. The recycling pathway is required for beta-lactamase induction in many Gram negative organisms and, in addition, we have recently observed that mutations in certain recycling genes result in autoaggregation and biofilm formation. Thus the pathway is of interest in the health related areas of resistance to penicillins and biofilm formation. Specific aims: Aim #1: Determine the pathway for utilization of N-acetylglucosamine in the absence of the N-acetylglucosamine kinase. We have already achieved the original goal of Aim 1, namely, Identify the kinase gene and demonstrate its role in reutilization of N-acetylglucosamine. Aim #2: Determine how E. coli degrades anhydro-N-acetylmuramic acid. Our recent results indicate that a kinase and an etherase may be involved. Hence our current efforts are aimed at purifying these activities in order to identify the genes responsible for the activities. Aim #3: Determine the true inducer of beta-lactamase. Aim #4: Determine how expression of antigen 43 is related to the recycling of murein tripeptide. Antigen 43 causes autoaggregation which facilitates biofilm formation. Deletion of either murein peptide ligase (mpl) or murein peptide amidase A (mpaA) results in production of tripeptide and antigen 43 suggesting that accumulation of the murein tripeptide, L-Ala-gamma-D-Glu-meso-diaminopimelic acid, may be involved.