Role of Ser216 in the mechanism of action of membrane-bound lytic transglycosylase B: Further evidence for substrate-assisted catalysis
Role of Ser216 in the mechanism of action of membrane-bound lytic transglycosylase B: Further evidence for substrate-assisted catalysis
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DOI：
10.1016/j.febslet.2007.09.037
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发表时间：
2007-10-16
期刊：
影响因子：
3.5
通讯作者：
Clarke, Anthony J.
中科院分区：
文献类型：
--
作者：
Reid, Christopher W.;Legaree, Blaine A.;Clarke, Anthony J.
裂解性转糖基酶裂解细菌细胞壁杂聚物肽聚糖中N-乙酰胞壁酸（MurNAc）和N-乙酰葡糖胺（GlcNAc）残基之间的β-（1 -> 4）-糖苷键，伴随形成1，6-脱水胞壁酰残基。基于序列比对，铜绿假单胞菌膜结合裂解性转糖基酶B（Mlt B）中的Ser 216被丙氨酸取代，以描述其在酶作用机制中的作用。Ser 216-> AlaMltB衍生物的比活性小于野生型酶的比活性的12%，而其底物结合亲和力几乎保持不变。这些数据与Ser 216在MltB的-1亚位点定位MurNAc上的N-乙酰基以参与底物辅助作用机制中的作用一致。(c)2007年欧洲生物化学学会联合会。Elsevier B. V.出版，保留所有权利。
Lytic transglycosylases cleave the beta-(1 -> 4)-glycosidic bond in the bacterial cell wall heteropolymer peptidoglycan between the N-acetylmuramic acid (MurNAc) and N-acetylglu-cosamine (GlcNAc) residues with the concomitant formation of a 1,6-anhydromuramoyl residue. Based on sequence alignments, Ser216 in Pseudomonas aeruginosa membrane-bound lytic transglycosylase B (MltB) was targeted for replacement with alanine to delineate its role in the enzyme's mechanism of action. The specific activity of the Ser216 -> Ala MltB derivative was less than 12% of that for the wild-type enzyme, while its substrate binding affinity remained virtually unaltered. These data are in agreement with a role of Ser216 in orienting the N-acetyl group on MurNAc at the -1 subsite of MltB for its participation in a substrate-assisted mechanism of action. (c) 2007 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.