Bifunctional ArsI Dioxygenase from Acidovorax sp. ST3 with Both Methylarsenite [MAs(III)] Demethylation and MAs(III) Oxidation Activities.
Environ Sci Technol
; 58(37): 16444-16453, 2024 Sep 17.
Article
en En
| MEDLINE
| ID: mdl-39226438
ABSTRACT
Methylated arsenicals, including highly toxic species, such as methylarsenite [MAs(III)], are pervasive in the environment. Certain microorganisms possess the ability to detoxify MAs(III) by ArsI-catalyzed demethylation. Here, we characterize a bifunctional enzyme encoded by the arsI gene from Acidovorax sp. ST3, which can detoxify MAs(III) through both the demethylation and oxidation pathways. Deletion of the 22 C-terminal amino acids of ArsI increased its demethylation activity while reducing the oxidation activity. Further deletion of 44 C-terminal residues enhanced the MAs(III) demethylation activity. ArsI has four vicinal cysteine pairs, with the first pair being necessary for MAs(III) demethylation, while at least one of the other three pairs contributes to MAs(III) oxidation. Molecular modeling and site-directed mutagenesis indicated that one of the C-terminal vicinal cysteine pairs is involved in modulating the switch between oxidase and demethylase activity. These findings underscore the critical role of the C-terminal region in modulating the enzymatic activities of ArsI, particularly in MAs(III) demethylation. This research reveals the structure-function relationship of the ArsI enzyme and advances our understanding of the MAs(III) metabolism in bacteria.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Oxidación-Reducción
/
Dioxigenasas
Idioma:
En
Revista:
Environ Sci Technol
Año:
2024
Tipo del documento:
Article
Pais de publicación:
Estados Unidos