title: 3-Carboxy-cis,cis-muconate lactonizing enzyme from Pseudomonas putida is homologous to the class II fumarase family: a new reaction in the evolution of a mechanistic motif.
abstract: The gene (pcaB) for 3-carboxymuconate lactonizing enzyme (CMLE; 3-carboxymuconate cycloisomerase; EC 5.5.1.2) from Pseudomonas putida has been cloned into pMG27NS, a temperature-sensitive expression vector, and expressed in Escherichia coli N4830. The specific activity and kinetic parameters of the recombinant CMLE were comparable to those previously reported. A comparison of the deduced amino acid sequence of CMLE with sequences available in the PIR and Genbank databases revealed that CMLE has highly significant sequence homology to the class II fumarase family, particularly to adenylosuccinate lyase from Bacillus subtilis. CMLE has no significant homology to muconate lactonizing enzyme (MLE) from P. putida, its sister enzyme in the beta-ketoadipate pathway. These findings fully corroborate a prediction made by us on the basis of mechanistic and stereochemical analyses of CMLE and MLE [Chari, R. V. J., Whitman, C. P., Kozarich, J. W., Ngai, K.-L., & Ornston, L. N. (1987) J. Am. Chem. Soc. 109, 5514-5519] and suggest that CMLE and MLE were recruited into this specialized pathway from two different enzyme families.
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park 20742.
authors.forename: S E
authors.initials: SE
authors.lastname: Williams
authors.forename: E M
authors.initials: EM
authors.lastname: Woolridge
authors.forename: S C
authors.initials: SC
authors.lastname: Ransom
authors.forename: J A
authors.initials: JA
authors.lastname: Landro
authors.forename: P C
authors.initials: PC
authors.lastname: Babbitt
authors.forename: J W
authors.initials: JW
authors.lastname: Kozarich
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D003001:Cloning, Molecular; D004269:DNA, Bacterial; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli; D005649:Fumarate Hydratase / Q000235:genetics*; D007700:Kinetics; D008969:Molecular Sequence Data; D010957:Plasmids; D016958:Pseudomonas putida / Q000201:enzymology* / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D004269:DNA, Bacterial; D005649:Fumarate Hydratase