期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 280, 期 49, 页码 40802-40812出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M506328200
关键词
-
LD- Carboxypeptidases ( EC 3.4.17.13) are named for their ability to cleave amide bonds between L- and D- amino acids, which occur naturally in bacterial peptidoglycan. They are specific for the link between meso- diaminopimelic acid and D- alanine and therefore degrade GlcNAc- MurNAc tetrapeptides to the corresponding tripeptides. As only the tripeptides can be reused as peptidoglycan building blocks, LD- carboxypeptidases are thought to play a role in peptidoglycan recycling. Despite the pharmaceutical interest in peptidoglycan biosynthesis, the fold and catalytic type of LD- carboxypeptidases are unknown. Here, we show that a previously uncharacterized open reading frame in Pseudomonas aeruginosa has LD- carboxypeptidase activity and present the crystal structure of this enzyme. The structure shows that the enzyme consists of an N-terminal beta-sheet and a C-terminal beta-barrel domain. At the interface of the two domains, Ser(115) adopts a highly strained conformation in the context of a strand-turn-helix motif that is similar to the nucleophilic elbow in alpha beta-hydrolases. Ser(115) is hydrogen- bonded to a histidine residue, which is oriented by a glutamate residue. All three residues, which occur in the order Ser-Glu-His in the amino acid sequence, are strictly conserved in naturally occurring LD- carboxypeptidases and cannot be mutated to alanines without loss of activity. We conclude that LD- carboxypeptidases are serine peptidases with Ser-His-Glu catalytic triads.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据