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ArxA, a new clade of arsenite oxidase within the DMSO reductase family of molybdenum oxidoreductases
Author(s) -
Zargar Kamrun,
Conrad Alison,
Bernick David L.,
Lowe Todd M.,
Stolc Viktor,
Hoeft Shelley,
Oremland Ronald S.,
Stolz John,
Saltikov Chad W.
Publication year - 2012
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2012.02722.x
Subject(s) - arsenite , biology , arsenate , clade , autotroph , microbiology and biotechnology , bacteria , phylogenetics , biochemistry , arsenic , genetics , gene , chemistry , organic chemistry
Summary Arsenotrophy, growth coupled to autotrophic arsenite oxidation or arsenate respiratory reduction, occurs only in the prokaryotic domain of life. The enzymes responsible for arsenotrophy belong to distinct clades within the DMSO reductase family of molybdenum‐containing oxidoreductases: specifically arsenate respiratory reductase, ArrA, and arsenite oxidase, AioA (formerly referred to as AroA and AoxB). A new arsenite oxidase clade, ArxA, represented by the haloalkaliphilic bacterium Alkalilimnicola ehrlichii strain MLHE‐1 was also identified in the photosynthetic purple sulfur bacterium Ectothiorhodospira sp. strain PHS‐1. A draft genome sequence of PHS‐1 was completed and an arx operon similar to MLHE‐1 was identified. Gene expression studies showed that arxA was strongly induced with arsenite. Microbial ecology investigation led to the identification of additional arxA ‐like sequences in Mono Lake and Hot Creek sediments, both arsenic‐rich environments in California. Phylogenetic analyses placed these sequences as distinct members of the ArxA clade of arsenite oxidases. ArxA‐like sequences were also identified in metagenome sequences of several alkaline microbial mat environments of Yellowstone National Park hot springs. These results suggest that ArxA‐type arsenite oxidases appear to be widely distributed in the environment presenting an opportunity for further investigations of the contribution of Arx‐dependent arsenotrophy to the arsenic biogeochemical cycle.