Functional Study of AcoX, an Unknown Protein Involved in Acetoin Catabolism

摘要

The function of AcoX,encoded by acoX existing in aco clusters which are responsible for acetoin catabolism in some microbes from the Kingdoms of Bacteria and Archaea,remained unknown till today.Although some AcoXs were annotated as ATP-NAD kinases in bioinformatics databases,AcoXs were found to form an independent family during evolution in this study.By bioinformatic analysis and molecular comparison,AcoX was postulated to have the catalytic function of acetoin phosphorylation.The AcoX from Pseudomonas putida KT2440 was expressed in Escherichia coli using the pET28a vector.The His-tagged AcoX was purified and digested by thrombin.The deconvolution of circular dichroism spectra using K2d algorithm indicates a ＞28％ and ＞14％ content for alpha and beta structures in AcoX,respectively.But unfortunately,not only the activities of NAD kinase,pyruvate kinase,and methylglyoxal synthase,but also the postulated enzymatic activity of acetoin kinase was not detected under all the conditions studied.