The identification of catalytic pentad in the haloalkane dehalogenase DhmA from Mycobacterium avium N85: reaction mechanism and molecular evolution
Language English Country United States Media print-electronic
Document type Journal Article
PubMed
17084094
DOI
10.1016/j.jsb.2006.09.004
PII: S1047-8477(06)00286-3
Knihovny.cz E-resources
- MeSH
- Models, Biological MeSH
- Hydrolases chemistry genetics isolation & purification metabolism MeSH
- Catalytic Domain * MeSH
- Evolution, Molecular MeSH
- Models, Molecular MeSH
- Molecular Sequence Data MeSH
- Mutagenesis, Site-Directed MeSH
- Mutant Proteins genetics isolation & purification MeSH
- Mycobacterium avium enzymology MeSH
- Sequence Homology, Amino Acid MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- haloalkane dehalogenase MeSH Browser
- Hydrolases MeSH
- Mutant Proteins MeSH
Haloalkane dehalogenase DhmA from Mycobacterium avium N85 showed poor expression and low stability when produced in Escherichia coli. Here, we present expression DhmA in newly constructed pK4RP rhodococcal expression system in a soluble and stable form. Site-directed mutagenesis was used for the identification of a catalytic pentad, which makes up the reaction machinery of all currently known haloalkane dehalogenases. The putative catalytic triad Asp123, His279, Asp250 and the first halide-stabilizing residue Trp124 were deduced from sequence comparisons. The second stabilizing residue Trp164 was predicted from a homology model. Five point mutants in the catalytic pentad were constructed, tested for activity and were found inactive. A two-step reaction mechanism was proposed for DhmA. Evolution of different types of catalytic pentads and molecular adaptation towards the synthetic substrate 1,2-dichloroethane within the protein family is discussed.
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