Open AccessResistance to arsenic compounds in microorganisms
Author(s) -
Cervantes Carlos,
Ji Guangyong,
Ramirez JoséLuis,
Silver Simon
Publication year - 1994
Publication title -
fems microbiology reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.91
H-Index - 212
eISSN - 1574-6976
pISSN - 0168-6445
DOI - 10.1111/j.1574-6976.1994.tb00145.x
Subject(s) - arsenite , arsenate , arsenic , biology , bacteria , efflux , plasmid , microbiology and biotechnology , biochemistry , enterobacter aerogenes , bacterial cell structure , gene , chemistry , genetics , escherichia coli , organic chemistry
Arsenic ions, frequently present as environmental pollutants, are very toxic for most microorganisms. Some microbial strains possess genetic determinants that confer resistance. In bacteria, these determinants are often found on plasmids, which has facilitated their study at the molecular level. Bacterial plasmids conferring arsenic resistance encode specific efflux pumps able to extrude arsenic from the cell cytoplasm thus lowering the intracellular concentration of the toxic ions. In Gram‐negative bacteria, the efflux pump consists of a two‐component ATPase complex. ArsA is the ATPase subunit and is associated with an integral membrane subunit, ArsB. Arsenate is enzymatically reduced to arsenite (the substrate of ArsB and the activator of ArsA) by the small cytoplasmic ArsC polypeptide. In Gram‐positive bacteria, comparable arsB and arsC genes (and proteins) are found, but arsA is missing. In addition to the wide spread plasmid arsenic resistance determinant, a few bacteria confer resistance to arsenite with a separate determinant for enzymatic oxidation of more‐toxic arsenite to less‐toxic arsenate. In contrast to the detailed information on the mechanisms of arsenic resistance in bacteria, little work has been reported on this subject in algae and fungi.