Structural and mechanistic analysis of trans-3-chloroacrylic acid dehalogenase activity
- UIC
Trans-3-chloroacrylic acid dehalogenase (CaaD) is a critical enzyme in the trans-1,3-dichloropropene (DCP) degradation pathway in Pseudomonas pavonaceae 170. This enzyme allows bacteria to use trans-DCP, a common component in commercially produced fumigants, as a carbon source. CaaD specifically catalyzes the fourth step of the pathway by cofactor-independent dehalogenation of a vinyl carbon-halogen bond. Previous studies have reported an X-ray structure of CaaD under acidic conditions with a covalent modification of the catalytic {beta}Pro1 residue. Here, the 1.7 {angstrom} resolution X-ray structure of CaaD under neutral (pH 6.5) conditions is reported without the presence of the covalent adduct. In this new structure, a substrate-like acetate molecule is bound within the active site in a position analogous to the putative substrate-binding site. Additionally, a catalytically important water molecule was identified, consistent with previously proposed reaction schemes. Finally, flexibility of the catalytically relevant side chain {alpha}Glu52 is observed in the structure, supporting its role in the catalytic mechanism.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1007059
- Journal Information:
- Acta Crystallogr. D, Vol. 64, Issue (12) ; 12, 2008; ISSN 0907-4449
- Country of Publication:
- United States
- Language:
- ENGLISH
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