Structural highlights
Publication Abstract from PubMedThe isomeric mixture of cis- and trans-1,3-dichloropropene constitutes the active component of a widely used nematocide known as Telone II(R). The mixture is processed by various soil bacteria to acetaldehyde through the 1,3-dichloropropene catabolic pathway. The pathway relies on an isomer-specific hydrolytic dehalogenation reaction catalyzed by cis- or trans-3-chloroacrylic acid dehalogenase, known respectively as cis-CaaD and CaaD. Previous sequence analysis and crystallographic studies of the native and covalently modified enzymes identified Pro-1, His-28, Arg-70, Arg-73, Tyr-103, and Glu-114 as key binding and catalytic residues in cis-CaaD. Mutagenesis of these residues confirmed their importance to the dehalogenation reaction. Crystal structures of the native enzyme (2.01A resolution) and the enzyme covalently modified at the Pro-1 nitrogen by 2-hydroxypropanoate (1.65A resolution) are reported here. Both structures are at a resolution higher than previously reported (2.75A and 2.1A resolution, respectively). The conformation of the covalent adduct is strikingly different from that previously reported due to its interaction with a 7-residue loop (Thr-32 to Leu-38). The participation of another active site residue, Arg-117, in catalysis and inactivation was also examined. The implications of the combined findings for the mechanisms of catalysis and inactivation are discussed. Crystal structures of native and inactivated cis-3-chloroacrylic acid dehalogenase: Implications for the catalytic and inactivation mechanisms.,Guo Y, Serrano H, Johnson WH Jr, Ernst S, Hackert ML, Whitman CP Bioorg Chem. 2010 Oct 20. PMID:21074239[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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