Download MendeleyKinetic and structural characterization of a cis-3-Chloroacrylic acid dehalogenase homologue in Pseudomonas sp. UW4: A potential step between subgroups in the tautomerase superfamily.
LeVieux, J.A., Baas, B.J., Kaoud, T.S., Davidson, R., Babbitt, P.C., Zhang, Y.J., Whitman, C.P.(2017) Arch Biochem Biophys 636: 50-56
- PubMed: 29111295
- DOI: https://doi.org/10.1016/j.abb.2017.10.018
- Primary Citation of Related Structures:
5UIF - PubMed Abstract:
A Pseudomonas sp. UW4 protein (UniProt K9NIA5) of unknown function was identified as similar to 4-oxalocrotonate tautomerase (4-OT)-like and cis-3-chloroacrylic acid dehalogenase (cis-CaaD)-like subgroups of the tautomerase superfamily (TSF). This protein lacks only Tyr-103 of the amino acids critical for cis-CaaD activity (Pro-1, His-28, Arg-70, Arg-73, Tyr-103, Glu-114). As it may represent an important variant of these enzymes, its kinetic and structural properties have been determined. The protein shows tautomerase activity with phenylenolpyruvate, but lacks native 4-OT activity and dehalogenase activity with the isomers of 3-chloroacrylic acid. It shows mostly low-level hydratase activity at pH 7.0, converting 2-oxo-3-pentynoate to acetopyruvate, consistent with cis-CaaD-like behavior. At pH 9.0, this compound results primarily in covalent modification of Pro-1, which is consistent with 4-OT-like behavior. These observations could reflect a pK a for Pro-1 that is closer to that of cis-CaaD (∼9.2) than to 4-OT (∼6.4). A structure of the native enzyme, at 2.6 Å resolution, highlights differences at the active site from those of 4-OT and cis-CaaD that add to our understanding of how contemporary TSF reactions and mechanisms may have diverged from a common 4-OT-like ancestor.
Organizational Affiliation:
Department of Molecular Biosciences, Austin, TX 78712, USA.
