The active repertoire of Escherichia coli peptidoglycan amidases varies with physiochemical environment
The active repertoire of Escherichia coli peptidoglycan amidases varies with physiochemical environment
复制标题
大肠杆菌肽聚糖酰胺酶的活性库随理化环境而变化
DOI：
10.1101/2020.10.19.344754
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
P. Levin
中科院分区：
文献类型：
--
作者：
Elizabeth A. Mueller;Abbygail G. Iken;M. A. Öztürk;Mirko Schmitz;Barbara Di Ventura;P. Levin
几乎所有的细菌都被包裹在肽聚糖细胞壁中，肽聚糖细胞壁是多糖链和短肽茎的基本交联基质。在革兰氏阴性模式生物大肠杆菌中，超过40种细胞壁降解酶和自溶素协调周质中肽聚糖囊的生长和分裂。这些酶中的许多对细胞壁代谢的精确贡献由于显著的明显冗余而仍然不清楚，特别是在细胞壁自溶素中。E.大肠杆菌产生三种主要的LytC-型-N-乙酰胞壁酰-L-丙氨酸酰胺酶，它们在胞质分裂期间分离新形成的子细胞中起作用。在这里，我们揭示了三个酰胺酶中的两个表现出生长介质依赖的活性变化。具体来说，我们报告酸性生长条件刺激AmiB-和在较小程度上，AmiC-活性。结合计算和遗传分析，我们证明了AmiB的低pH依赖性刺激需要三种周质酰胺酶激活剂：EnvC，NlpD和YgeR。总之，我们的研究结果支持重叠，但不是多余的，E。大肠杆菌酰胺酶在细胞分离和照明的理化环境作为细胞壁酶活性的重要介质。重要性青霉素和相关的β-内酰胺类抗生素靶向细菌细胞壁合成是世界上最常用的处方抗菌药物之一。然而，抗生素耐药性和耐受性的上升危及其持续的临床使用。开发新的细胞壁活性治疗剂，包括靶向细胞壁自溶素的治疗剂，部分由于高水平的表观酶冗余而受到阻碍。在这项研究中，我们报告了一个子集的E。在细胞分裂期间参与细胞分离的大肠杆菌酰胺酶不是多余的，而是在不同pH环境中生长期间优先具有活性。具体地说，我们发现E.大肠杆菌酰胺酶AmiB和AmiC被酸性pH激活。三个半冗余的周质调节因子NlpD、EnvC和YgeR共同介导酰胺酶活性的低pH依赖性刺激。这一发现有助于我们了解细胞壁如何在不同的环境条件下保持健壮，并揭示了开发条件特异性抗菌剂的机会。
Nearly all bacteria are encased in a peptidoglycan cell wall, an essential crosslinked matrix of polysaccharide strands and short peptide stems. In the Gram-negative model organism Escherichia coli, more than forty cell wall synthases and autolysins coordinate the growth and division of the peptidoglycan sacculus in the periplasm. The precise contribution of many of these enzymes to cell wall metabolism remains unclear due to significant apparent redundancy, particularly among the cell wall autolysins. E. coli produces three major LytC-type-N-acetylmuramoyl-L-alanine amidases, which share a role in separating the newly formed daughter cells during cytokinesis. Here, we reveal two of the three amidases exhibit growth medium-dependent changes in activity. Specifically, we report acidic growth conditions stimulate AmiB—and to a lesser extent, AmiC—activity. Combining computational and genetic analysis, we demonstrate that low pH-dependent stimulation of AmiB requires three periplasmic amidase activators: EnvC, NlpD, and YgeR. Altogether, our findings support overlapping, but not redundant, roles for the E. coli amidases in cell separation and illuminate the physiochemical environment as an important mediator of cell wall enzyme activity. IMPORTANCE Penicillin and related β-lactam antibiotics targeting the bacterial cell wall synthesis are among the most commonly prescribed antimicrobials worldwide. However, rising rates of antibiotic resistance and tolerance jeopardize their continued clinical use. Development of new cell wall active therapeutics, including those targeting cell wall autolysins, has been stymied in part due to high levels of apparent enzymatic redundancy. In this study, we report a subset of E. coli amidases involved in cell separation during cell division are not redundant and instead are preferentially active during growth in distinct pH environments. Specifically, we discover E. coli amidases AmiB and AmiC are activated by acidic pH. Three semi-redundant periplasmic regulators—NlpD, EnvC, and YgeR—collectively mediate low pH-dependent stimulation of amidase activity. This discovery contributes to our understanding of how the cell wall remains robust across diverse environmental conditions and reveals opportunities for the development of condition-specific antimicrobial agents.
影响因子：
8.8
作者：
Lonergan, Zachery R.;Nairn, Brittany L.;Skaar, Eric P.
通讯作者：
Skaar, Eric P.
影响因子：
5.6
作者：
Cohen, Daniel N.;Sham, Yuk Y.;Haugstad, Greg D.;Xiang, Ye;Rossmann, Michael G.;Anderson, Dwight L.;Popham, David L.
通讯作者：
Popham, David L.