MUROPEPTIDE RECYCLING PATHWAY & BETA LACTAMASE INDUCTION

本提案的主要目的是阐明所用的途径 由E.大肠杆菌中回收的肽，以确定功能回收 在细胞的生命中起作用， 在β-内酰胺酶诱导过程中。 这些目标来自我们的 初步结果支持以下初步结论：（1） AmpG是β-内酰胺酶诱导所必需的一种通透酶 用于回收细胞壁成分。 (2)AmpG最有可能 转运N-乙酰葡糖胺基-β 1-4，1，6脱水-N-乙酰胞壁酰-L- 丙氨酰-D-谷氨酰-（L）-内消旋-二氨基庚二酸（GlcNAc-anhMurNAc-L-ala-D-） glu-DAP）进入细胞质。 (3)AmpD，β-内酰胺酶所需 感应加热对于回收也是必不可少的。 (4)ampD突变体积累 大量的anhMurNAc-L-ala-D-glu-DAP表明它是一种诱导 配体。 (5)AmpD是anhMurNAc-1-ala酰胺酶。 想必 AmpD酰胺酶释放的三肽通过一种新的酶添加到UDPMurNAc中， 发现三肽添加酶，从而重新引入L-ala-D-glu-， DAP进入生物合成途径。 (6)G1cNAc-anhMurNAC-L-ala-D-glu-DAP 可能是β-内酰胺酶的另一种诱导剂。 基于这些新 根据过去16个月的成果，具体目标是： 1. 研究和表征回收中的4个预测步骤 途径，即：AmpG通透酶、β-N-乙酰氨基葡萄糖苷酶、AmpD 酰胺酶和假设的三肽添加酶。 2. 鉴定β-内酰胺酶诱导中涉及的胞肽， 以进一步表征它们在β-内酰胺酶诱导中的作用。 3. 寻找循环在细胞生命中的作用。

The principal objectives of this proposal are to elucidate the pathway used by E. coli for recycling muropeptides, to determine the function recycling serves in the life of the cell and to characterize the role of muropeptides in the beta-lactamase induction process. These objectives follow from our preliminary results which support the following tentative conclusions: (1) AmpG, which is required for beta-lactamase induciton, is a permease required for recycling cell wall components. (2) AmpG most likely transports N-acetylglucosaminyl-beta 1-4, 1,6 anhydro-N-acetylmuramyl-L- alanyl-D-glutamyl-(L)-meso-diaminopimelic acid (G1cNAc-anhMurNAc-L-ala-D- glu-DAP) into the cytoplasm. (3) AmpD, required for beta-lactamase inducibility is also essential for recycling. (4) ampD mutants accumulate huge amounts of anhMurNAc-L-ala-D-glu-DAP indicating that it is an inducing ligand. (5) AmpD is an anhMurNAc-1-ala amidase. Presumably the tripeptide released by the AmpD amidase is added to UDPMurNAc by a yet to be discovered tripeptide-adding enzyme thereby reintroducing L-ala-D-glu- DAP into the biosynthetic pathway. (6) G1cNAc-anhMurNAC-L-ala-D-glu-DAP is probably another inducer of beta-lactamase. Thus, based on these new results of the past 16 months, the specific aims are: 1. To study and characterize the 4 predicted steps in the recycling pathway, namely: AmpG permease, beta-N-acetylglucosaminidase, AmpD amidase, and the hypothetical tripeptide-adding enzyme. 2. To identify the muropeptides involved in beta-lactamase induction and to further characterize their role in beta-lactamase induction. 3. To search for a role of recycling in the life of the cell.