Shared catalysis in virus entry and bacterial cell wall depolymerization.
Shared catalysis in virus entry and bacterial cell wall depolymerization.
复制标题
DOI：
10.1016/j.jmb.2009.02.001
复制
发表时间：
2009-04-03
影响因子：
5.6
通讯作者：
Popham, David L.
中科院分区：
文献类型：
--
作者：
Cohen, Daniel N.;Sham, Yuk Y.;Haugstad, Greg D.;Xiang, Ye;Rossmann, Michael G.;Anderson, Dwight L.;Popham, David L.
细菌病毒进入和细胞壁解聚需要分解肽聚糖(PG)，这是一种包裹在细菌细胞周围的多肽交联多糖基质。溶葡萄球菌酶是一种PG裂解酶(自溶酶)，其结构研究表明，活性部位的残基促进了水解，但该反应的明确机制仍未解决。β-Sheet的活性部位残基和结构模式在溶葡萄球菌同源物(如金黄色葡萄球菌的LytM)和基因产物13的C末端结构域(Gp13)之间是保守的，gp13是枯草杆菌噬菌体φ29尾端的一种蛋白质。用高效液相色谱法测定了gp13对PG和多肽的活性，发现gp13是一种D，D-内肽酶，可以裂解多肽的交联键。对枯草杆菌交联肽gp13活性位点的计算模拟表明，Asp195可能促进剪切键的激活，而His247定位于介导亲核细胞的生成。这是我们所知的第一个锌金属多肽酶及其底物的模型。发现gp13的残基Asp195对锌离子的结合和催化起关键作用，可用丙氨酸或半胱氨酸进行置换突变。圆二色谱和粒子诱导的X射线发射光谱表明，Cys突变体保持了蛋白质的总折叠和锌结合，而Ala突变体则减少了蛋白质的折叠和结合。这些发现共同支持了一个模型，即gp13中的Asp195和His247以及LytM和LysoStphin活性位点上的同源残基促进了使PG交联的多肽底物的水解。因此，这些自溶酶和噬菌体进入酶具有共同的化学作用机制。
Bacterial virus entry and cell wall depolymerization require the breakdown of peptidoglycan (PG), the peptide cross-linked polysaccharide matrix that surrounds bacterial cells. Structural studies of lysostaphin, a PG lytic enzyme (autolysin), have suggested that residues in the active site facilitate hydrolysis, but a clear mechanism for this reaction has remained unsolved. The active site residues and a structural pattern of β-sheets are conserved among lysostaphin homologs (such as LytM of Staphylococcus aureus) and the C-terminal domain of gene product 13 (gp13), a protein at the tail tip of the Bacillus subtilis bacteriophage φ29. gp13 activity on PG and muropeptides was assayed using high performance liquid chromatography, and gp13 was found to be a D,D-endopeptidase that cleaved the peptide cross-link. Computational modeling of the B. subtilis cross-linked peptide into the gp13 active site suggested that Asp195 may facilitate scissile bond activation and His247 is oriented to mediate nucleophile generation. This is the first model of a Zn2+-metallopeptidase and its substrate to our knowledge. Residue Asp195 of gp13 was found to be critical for Zn2+-binding and catalysis by substitution mutagenesis with Ala or Cys. Circular dichroism and particle induced X-ray emission spectroscopy showed that the general protein folding and Zn2+-binding was maintained in the Cys mutant but reduced in the Ala mutant. These findings together support a model where the Asp195 and His247 in gp13 and homologous residues in the LytM and lysostaphin active sites facilitate hydrolysis of the peptide substrate that cross-links PG. Thus, these autolysins and phage entry enzymes have a shared chemical mechanism of action.
登录
查看更多内容
影响因子：
8
作者：
Bochtler, M;Odintsov, SG;Sabala, I
通讯作者：
Sabala, I
影响因子：
4.8
作者：
Boulanger, Pascale;Jacquot, Pierre;Letellier, Lucienne
通讯作者：
Letellier, Lucienne
影响因子：
2.9
作者：
Firczuk, Malgorzata;Bochtler, Matthias
通讯作者：
Bochtler, Matthias
影响因子：
4.8
作者：
Lu, JZQ;Fujiwara, T;Sakon, J
通讯作者：
Sakon, J
影响因子：
7.3
作者：
Kontoyianni, M;McClellan, LM;Sokol, GS
通讯作者：
Sokol, GS