title: Evolutionary divergence of co-selected beta-ketoadipate enol-lactone hydrolases in Acinetobacter calcoaceticus.
abstract: Muconolactone isomerase (EC 5.3.3.4) and beta-ketoadipate enol-lactone hydrolase (EC 3.1.1.24) mediate consecutive catabolic steps in bacteria. Separately inducible beta-ketoadipate enol-lactone hydrolases I and II are formed in representatives of Acinetobacter calcoaceticus. When subjected to DEAE-cellulose chromatography, Acinetobacter enol-lactone hydrolase I displays heterogeneous behavior which, in whole or in part, appears to be due to modifications of sulfhydryl groups in the protein; the enzyme is unusual in that its NH2-terminal amino acid is cysteine. Comparison of the NH2-terminal amino acid sequence of Acinetobacter enollactone hydrolase I, reported here, with the corresponding amino acid sequences of Acinetobacter enollactone hydrolase II and Pseudomonas enol-lactone hydrolase indicates that all three proteins have diverged widely from a common evolutionary origin. Sequence comparisons suggest that divergence of the Acinetobacter enol-lactone hydrolase structural genes was achieved by substitution with DNA derived from an ancestral muconolactone isomerase structural gene.
mesh_terms: D000150:Acinetobacter / Q000201:enzymology* / Q000235:genetics; D000272:Adipates / Q000032:analysis; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis*; D001426:Bacterial Proteins; D005075:Biological Evolution; D019748:Carbon-Carbon Double Bond Isomerases; D002265:Carboxylic Ester Hydrolases / Q000032:analysis*; D002848:Chromatography, DEAE-Cellulose; D005796:Genes; D007527:Isoenzymes / Q000032:analysis*; D007535:Isomerases / Q000032:analysis
chemical_list: D000272:Adipates; D000596:Amino Acids; D001426:Bacterial Proteins; D007527:Isoenzymes; D002265:Carboxylic Ester Hydrolases; C021927:3-oxoadipate enol-lactonase; D007535:Isomerases; D019748:Carbon-Carbon Double Bond Isomerases; C100087:muconolactone delta-isomerase