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Role of Ser216 in the mechanism of action of membrane‐bound lytic transglycosylase B: Further evidence for substrate‐assisted catalysis
Author(s) -
Reid Christopher W.,
Legaree Blaine A.,
Clarke Anthony J.
Publication year - 2007
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.09.037
Subject(s) - peptidoglycan , lytic cycle , glycosidic bond , residue (chemistry) , chemistry , enzyme , stereochemistry , biochemistry , alanine , bacterial cell structure , mechanism of action , substrate (aquarium) , amino acid , bacteria , biology , ecology , virus , genetics , virology , in vitro
Lytic transglycosylases cleave the β‐(1 → 4)‐glycosidic bond in the bacterial cell wall heteropolymer peptidoglycan between the N ‐acetylmuramic acid (MurNAc) and N ‐acetylglucosamine (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.