Muropeptide Recycling Pathway & Beta Lactamase Induction

描述(申请人提供)：令人惊讶的是，大肠杆菌每一代都能从侧壁降解60%以上的粘连蛋白(肽聚糖)，并能够重复利用这些成分。这个过程被称为回收利用。这项研究的目的是鉴定和鉴定大肠杆菌用来重复利用细胞壁肽聚糖成分的所有酶。回收涉及10多种酶，这些酶似乎没有其他作用，只是促进毛尿素组分的分解和再利用。一些悬而未决的问题仍有待回答，以便充分了解这一进程。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被膜的形成。因此，该途径在青霉素耐药和生物被膜形成的健康相关领域具有重要意义。具体目的：目的#1：确定在没有N-乙酰氨基葡萄糖的情况下利用N-乙酰氨基葡萄糖的途径。我们已经实现了目标1的最初目标，即鉴定该激酶基因，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脱水-N-乙酰胞壁酸。我们最近的研究结果表明，可能与一种激酶和一种乙醚酶有关。因此，我们目前的努力旨在纯化这些活动，以确定导致这些活动的基因。目的#3：确定β-内酰胺酶的真正诱导物。目的#4：确定抗原43的表达与肌动蛋白三肽循环的关系。抗原43引起自我聚集，从而促进生物膜的形成。肌动蛋白多肽连接酶(Mpl)或肌动蛋白多肽酰胺酶A(Mpaa)缺失均可产生三肽和抗原43，提示肌动蛋白三肽L-丙氨酸-γ-D-谷氨酸-中位二氨基戊二酸的蓄积可能参与了这一过程。

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.