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Crystal structure and molecular mechanism of an aspartate/glutamate racemase from Escherichia coli O157
Author(s) -
Liu Xiuhua,
Gao Fei,
Ma Yinliang,
Liu Shuang,
Cui Yaqi,
Yuan Zenglin,
Kang Xianjiang
Publication year - 2016
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 - 10.1002/1873-3468.12148
Subject(s) - active site , racemization , stereochemistry , escherichia coli , chemistry , crystal structure , transferase , catalysis , glutamate receptor , biochemistry , enzyme , crystallography , receptor , gene
EcL ‐DER, the aspartate/glutamate racemase from the pathogen Escherichia coli O157, exhibits racemase activity for l ‐aspartate and l ‐glutamate. This study reports the crystal structures of apo‐ EcL ‐DER, the EcL ‐DER‐ l ‐aspartate and the EcL ‐DER‐ d ‐aspartate complexes. The EcL ‐DER structure contains two domains, forming pseudo‐mirror symmetry in the active site. A unique catalytic pair consisting of Thr 83 and Cys 197 exists in the active site. The characteristic conformations of l ‐Asp and d ‐Asp in the active site provide a straight structural evidence for the racemization mechanism of EcL ‐DER. In addition, the diversity of catalytic pairs implies that PLP‐independent amino acid racemases adopt various catalytic mechanisms and are classified into different subgroups.