Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, USA.
Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, USA
mBio. 2020 Mar 3;11(2):e03315-19. doi: 10.1128/mBio.03315-19.
Synthesis and cleavage of the cell wall polymer peptidoglycan (PG) are carefully orchestrated processes and are essential for the growth and survival of bacteria. Yet, the function and importance of many enzymes that act on PG in remain to be elucidated. We demonstrate that the activity of the -acetylmuramyl-l-alanine amidase Ami1 is dispensable for cell division in yet contributes to the bacterium's ability to persist during chronic infection in mice. Furthermore, the d,l-endopeptidase RipA, a predicted essential enzyme, is dispensable for the viability of but required for efficient cell division and Depletion of RipA sensitizes to rifampin and to cell envelope-targeting antibiotics. Ami1 helps sustain residual cell division in cells lacking RipA, but the partial redundancy provided by Ami1 is not sufficient during infection, as depletion of RipA prevents from replicating in macrophages and leads to dramatic killing of the bacteria in mice. Notably, RipA is essential for persistence of in mice, suggesting that cell division is required during chronic mouse infection. Despite the multiplicity of enzymes acting on PG with redundant functions, we have identified two PG hydrolases that are important for to replicate and persist in the host. Tuberculosis (TB) is a major global heath burden, with 1.6 million people succumbing to the disease every year. The search for new drugs to improve the current chemotherapeutic regimen is crucial to reducing this global health burden. The cell wall polymer peptidoglycan (PG) has emerged as a very successful drug target in bacterial pathogens, as many currently used antibiotics target the synthesis of this macromolecule. However, the multitude of genes encoding PG-synthesizing and PG-modifying enzymes with apparent redundant functions has hindered the identification of novel drug targets in PG synthesis in Here, we demonstrate that two PG-cleaving enzymes are important for virulence of In particular, the d,l-endopeptidase RipA represents a potentially attractive drug target, as its depletion results in the clearance of from the host and renders the bacteria hypersusceptible to rifampin, a frontline TB drug, and to several cell wall-targeting antibiotics.
细胞壁聚合物肽聚糖（PG）的合成和裂解是精心协调的过程，对细菌的生长和存活至关重要。然而，许多作用于 PG 的酶的功能和重要性仍有待阐明。我们证明，-乙酰基胞壁酰-L-丙氨酸酰胺酶 Ami1 的活性对于 分裂是可有可无的，但有助于细菌在慢性感染中存活。此外，d,l-内肽酶 RipA，一种预测的必需酶，对于 的活力是可有可无的，但对于有效的细胞分裂是必需的，并且 RipA 的耗尽使 对利福平敏感，并对细胞包膜靶向抗生素敏感。Ami1 有助于维持缺乏 RipA 的细胞的残余分裂，但 Ami1 提供的部分冗余在感染期间是不够的，因为 RipA 的耗尽阻止了 在巨噬细胞中复制，并导致细菌在小鼠中急剧死亡。值得注意的是，RipA 对于 在小鼠中的持续存在是必需的，这表明细胞分裂在慢性小鼠感染期间是必需的。尽管有许多具有冗余功能的作用于 PG 的酶，但我们已经鉴定出两种 PG 水解酶，它们对于 复制和在宿主中持续存在是重要的。结核病（TB）是一个主要的全球健康负担，每年有 160 万人死于该疾病。寻找新的药物来改善目前的化疗方案对于降低这一全球健康负担至关重要。细胞壁聚合物肽聚糖（PG）已成为细菌病原体中非常成功的药物靶点，因为许多现有的抗生素都针对这种大分子的合成。然而，许多编码 PG 合成和 PG 修饰酶的基因具有明显的冗余功能，这阻碍了在 PG 合成中鉴定新的药物靶点。在这里，我们证明两种 PG 裂解酶对于 的毒力很重要。特别是，d,l-内肽酶 RipA 代表了一个有吸引力的药物靶点，因为其耗尽导致从宿主中清除 ，并使细菌对利福平（一种一线结核病药物）和几种细胞壁靶向抗生素高度敏感。
