Peptidoglycan (PG) is a major component of the bacterial cell wall, forming a mesh-like structure enwrapping the bacteria that is essential for maintaining structural integrity and providing support for anchoring other components of the cell envelope. PG biogenesis is highly dynamic and requires multiple enzymes, including several hydrolases that cleave glycosidic or amide bonds in the PG. This work describes the structural and functional characterization of an NlpC/P60-containing peptidase from Photobacterium damselae subsp. piscicida (Phdp), a Gram-negative bacterium that causes high mortality of warm-water marine fish with great impact for the aquaculture industry. PnpA (Photobacterium NlpC-like protein A) has a four-domain structure with a hydrophobic and narrow access to the catalytic center and specificity for the γ-d-glutamyl-meso-diaminopimelic acid bond. However, PnpA does not cleave the PG of Phdp or PG of several Gram-negative and Gram-positive bacterial species. Interestingly, it is secreted by the Phdp type II secretion system and degrades the PG of Vibrio anguillarum and Vibrio vulnificus. This suggests that PnpA is used by Phdp to gain an advantage over bacteria that compete for the same resources or to obtain nutrients in nutrient-scarce environments. Comparison of the muropeptide composition of PG susceptible and resistant to the catalytic activity of PnpA showed that the global content of muropeptides is similar, suggesting that susceptibility to PnpA is determined by the three-dimensional organization of the muropeptides in the PG.

中文翻译：

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来自发光杆菌亚种的分泌型 NlpC/P60 内肽酶。 piscicida 裂解潜在竞争细菌的肽聚糖


肽聚糖 (PG) 是细菌细胞壁的主要成分，形成包裹细菌的网状结构，这对于维持结构完整性和为锚定细胞包膜其他成分提供支持至关重要。 PG 生物发生是高度动态的，需要多种酶，包括几种裂解 PG 中糖苷键或酰胺键的水解酶。这项工作描述了来自damselae 发光杆菌亚种的含有 NlpC/P60 的肽酶的结构和功能特征。 piscicida ( Phdp ) 是一种革兰氏阴性细菌，可导致温水海水鱼类高死亡率，对水产养殖业产生巨大影响。 PnpA（ Photobacter N lpC 样蛋白A ）具有四结构域结构，具有疏水性、通往催化中心的狭窄通道以及对 γ -d-谷氨酰-内消旋-二氨基庚二酸键的特异性。然而，PnpA 不会切割Phdp的 PG 或几种革兰氏阴性和革兰氏阳性细菌的 PG。有趣的是，它是由Phdp II 型分泌系统分泌的，可降解鳗弧菌和创伤弧菌的 PG。这表明Phdp利用 PnpA 来获得相对于竞争相同资源的细菌的优势，或在营养稀缺的环境中获取营养。 比较对 PnpA 催化活性敏感和抗性的 PG 的壁肽组成表明，壁肽的总体含量相似，这表明对 PnpA 的敏感性是由 PG 中壁肽的三维组织决定的。