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Abstract：
Most bacteria surround themselves with a cell wall, a strong meshwork consisting primarily of the polymerized aminosugar peptidoglycan (PG). PG is essential for structural maintenance of bacterial cells, and thus for viability. PG is also constantly synthesized and turned over; the latter process is mediated by PG cleavage enzymes, for example, the endopeptidases (EPs). EPs themselves are essential for growth but also promote lethal cell wall degradation after exposure to antibiotics that inhibit PG synthases (e.g., β-lactams). Thus, EPs are attractive targets for novel antibiotics and their adjuvants. However, we have a poor understanding of how these enzymes are regulated in vivo, depriving us of novel pathways for the development of such antibiotics. Here, we have solved crystal structures of the LysM/M23 family peptidase ShyA, the primary EP of the cholera pathogen Vibrio cholerae Our data suggest that ShyA assumes two drastically different conformations: a more open form that allows for substrate binding and a closed form, which we predicted to be catalytically inactive. Mutations expected to promote the open conformation caused enhanced activity in vitro and in vivo, and these results were recapitulated in EPs from the divergent pathogens Neisseria gonorrheae and Escherichia coli Our results suggest that LysM/M23 EPs are regulated via release of the inhibitory Domain 1 from the M23 active site, likely through conformational rearrangement in vivo.
摘要：
大多数细菌都被细胞壁包围，主要由聚合的氨基糖肽聚糖（PG）组成的强网状物。PG对于细菌细胞的结构维持至关重要，因此，为了生存能力。PG也不断合成和翻转;后一个过程是由PG切割酶介导的，例如,内肽酶（EP）。EP本身对于生长至关重要，但在暴露于抑制PG合酶的抗生素后也会促进致死细胞壁降解（例如，β-内酰胺)。因此，EP是新型抗生素及其佐剂的有吸引力的靶标。然而,我们对这些酶在体内是如何被调节的知之甚少，剥夺了我们开发这种抗生素的新途径。这里,我们已经解决了LysM/M23家族肽酶ShyA的晶体结构，霍乱病原体霍乱弧菌的主要EP我们的数据表明，ShyA假设两种截然不同的构象：允许底物结合的更开放的形式和封闭的形式，我们预测是无催化活性的。预期促进开放构象的突变导致体外和体内活性增强，这些结果在来自不同病原体淋病奈瑟氏球菌和大肠杆菌的EPs中进行了概述。我们的结果表明，LysM/M23EPs是通过从M23活性位点释放抑制域1来调节的，可能通过体内构象重排。
