Institute of Biostructures and Bioimaging (IBB), CNR, 80134 Naples, Italy.
Cells. 2019 Jun 18;8(6):609. doi: 10.3390/cells8060609.
In preparation for division, bacteria replicate their DNA and segregate the newly formed chromosomes. A division septum then assembles between the chromosomes, and the mother cell splits into two identical daughters due to septum degradation. A major constituent of bacterial septa and of the whole cell wall is peptidoglycan (PGN), an essential cell wall polymer, formed by glycan chains of β-(1-4)-linked--acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc), cross-linked by short peptide stems. Depending on the amino acid located at the third position of the peptide stem, PGN is classified as either Lys-type or meso-diaminopimelic acid (DAP)-type. Hydrolytic enzymes play a crucial role in the degradation of bacterial septa to split the cell wall material shared by adjacent daughter cells to promote their separation. In mycobacteria, a key PGN hydrolase, belonging to the NlpC/P60 endopeptidase family and denoted as RipA, is responsible for the degradation of septa, as the deletion of the gene encoding for this enzyme generates abnormal bacteria with multiple septa. This review provides an update of structural and functional data highlighting the central role of RipA in mycobacterial cytokinesis and the fine regulation of its catalytic activity, which involves multiple molecular partners.
为了分裂，细菌复制它们的 DNA 并将新形成的染色体分开。然后，一个分裂隔膜在染色体之间组装，由于隔膜降解，母细胞分裂成两个相同的子细胞。肽聚糖 (PGN) 是细菌隔膜和整个细胞壁的主要成分，是一种必需的细胞壁聚合物，由 β-(1-4)-连接的--乙酰葡萄糖胺 (GlcNAc) 和 N-乙酰胞壁酸 (MurNAc) 的糖链组成，由短肽主干交联。根据肽主干上第三个位置的氨基酸，PGN 分为赖氨酸型或 meso-二氨基庚二酸 (DAP)-型。水解酶在细菌隔膜的降解中起着至关重要的作用，将相邻子细胞共享的细胞壁物质分解，促进它们的分离。在分枝杆菌中，一种关键的 PGN 水解酶，属于 NlpC/P60 内切蛋白酶家族，称为 RipA，负责隔膜的降解，因为编码该酶的基因缺失会产生具有多个隔膜的异常细菌。这篇综述提供了结构和功能数据的最新更新，强调了 RipA 在分枝杆菌细胞分裂中的核心作用以及其催化活性的精细调节，这涉及多个分子伴侣。
