Crystal Structure of Murein-Tripeptide Amidase MpaA from Escherichia coli O157 at 2.6 Å Resolution

• Published in: Protein and peptide letters Vol. 24; no. 2; p. 181
• Main Authors: Ma, Yinliang, Bai, Guohui, Cui, Yaqi, Zhao, Jing, Yuan, Zenglin, Liu, Xiuhua
• Format: Journal Article
• Language: English
• Published: Netherlands 01.02.2017
• Subjects: Catalytic Domain; Cloning, Molecular - methods; Crystallography, X-Ray; Endopeptidases - chemistry; Endopeptidases - genetics; Endopeptidases - metabolism; Escherichia coli O157 - chemistry; Escherichia coli O157 - enzymology; Escherichia coli O157 - genetics; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Models, Molecular; Peptidoglycan; Protein Binding; Protein Structure, Secondary; Mtp; crystal structure; E. coli O157; mtp amidase; MpaA; PG
• ISSN: 1875-5305
• DOI: 10.2174/0929866523666161128153128

Peptidoglycan (PG) is an essential component of the cell wall, and undergoes reconstruction by various PG hydrolases during cell growth, development and division. The murein- tripeptide (Mtp) amidase MpaA belongs to PG hydrolase family and is responsible for cleaving the γ-D-Glumeso- Dap amide bond in the Mtp released during PG turnover. The current paper reports the crystal structure of MpaA from Escherichia coli (E. coli) O157 at 2.6 Å resolution. The asymmetric unit consists of two protein molecules and each monomer represents the common α/β fold of metallocarboxypeptidases (MCP). The Tyr133-Asp143 loop appears to mediate the entrance and binding of the substrate into the active groove. A structural comparison of MpaA with its homologue from Vibrio harveyi showed that MpaA has narrower active pocket entrance with a smaller surface opening, which is determined by the Val204-Thr211 loop. The reported structure provides a starting point for the molecular mechanism of MpaA in a significant human pathogen.