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Investigating the mechanism of ADP ‐forming acetyl‐CoA synthetase from the protozoan parasite Entamoeba histolytica
Author(s) -
Jones Cheryl P.,
Khan Kirin,
IngramSmith Cheryl
Publication year - 2017
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 - 10.1002/1873-3468.12573
Subject(s) - entamoeba histolytica , enzyme , entamoeba , protein subunit , biochemistry , chemistry , phosphorylation , mechanism (biology) , active site , stereochemistry , biology , gene , microbiology and biotechnology , philosophy , epistemology
ADP ‐forming acetyl‐CoA synthetase ( ACD ) catalyzes the interconversion of acetyl‐CoA and acetate. The related succinyl‐CoA synthetase follows a three‐step mechanism involving a single phosphoenzyme, but a novel four‐step mechanism with two phosphoenzyme intermediates was proposed for Pyrococcus ACD . Characterization of enzyme variants of Entamoeba ACD in which the two proposed phosphorylated His residues were individually altered revealed that only His252 is essential for enzymatic activity. Analysis of variants altered at two residues proposed to interact with the phosphohistidine loop that swings between distinct parts of the active site are consistent with a mechanism involving a single phosphoenzyme intermediate. Our results suggest ACD s with different subunit structures may employ slightly different mechanisms to bridge the span between active sites I and II .