Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, NE2 4AX Newcastle upon Tyne, UK.
Sci Adv. 2020 Jul 22;6(30):eabb5614. doi: 10.1126/sciadv.abb5614. eCollection 2020 Jul.
Peptidoglycan (PG) is essential in most bacteria. Thus, it is often targeted by various assaults, including interbacterial attacks via the type VI secretion system (T6SS). Here, we report that the Gram-negative bacterium strain ATCC 17978 produces, secretes, and incorporates the noncanonical d-amino acid d-lysine into its PG during stationary phase. We show that PG editing increases the competitiveness of during bacterial warfare by providing immunity against peptidoglycan-targeting T6SS effectors from various bacterial competitors. In contrast, we found that d-Lys production is detrimental to pathogenesis due, at least in part, to the activity of the human enzyme d-amino acid oxidase (DAO), which degrades d-Lys producing HO toxic to bacteria. Phylogenetic analyses indicate that the last common ancestor of had the ability to produce d-Lys. However, this trait was independently lost multiple times, likely reflecting the evolution of as a human pathogen.
肽聚糖（PG）是大多数细菌所必需的。因此，它经常成为各种攻击的目标，包括通过 VI 型分泌系统（T6SS）进行的细菌间攻击。在这里，我们报告革兰氏阴性菌 株 ATCC 17978 在静止期产生、分泌并将非典型的 D-氨基酸 D-赖氨酸掺入其 PG 中。我们表明，PG 编辑通过提供对来自各种细菌竞争者的靶向 PG 的 T6SS 效应物的免疫，增加了 在细菌战中的竞争力。相比之下，我们发现由于人类酶 D-氨基酸氧化酶（DAO）的活性，D-赖氨酸的产生对发病机制有害，该酶降解 D-赖氨酸产生对细菌有毒的 HO。系统发育分析表明， 的最后一个共同祖先具有产生 D-赖氨酸的能力。然而，这种特性多次独立丢失，可能反映了 作为人类病原体的进化。
