The identification of catalytic pentad in the haloalkane dehalogenase DhmA from Mycobacterium avium N85: reaction mechanism and molecular evolution.
J Struct Biol
; 157(2): 384-92, 2007 Feb.
Article
en En
| MEDLINE
| ID: mdl-17084094
ABSTRACT
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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Bases de datos:
MEDLINE
Asunto principal:
Dominio Catalítico
/
Hidrolasas
/
Mycobacterium avium
Tipo de estudio:
Diagnostic_studies
/
Prognostic_studies
Idioma:
En
Revista:
J Struct Biol
Asunto de la revista:
BIOLOGIA MOLECULAR
Año:
2007
Tipo del documento:
Article
País de afiliación:
República Checa