Open AccessAnalysis of Genes Involved in Arsenic Resistance in Corynebacterium glutamicum ATCC 13032
Author(s) -
Efrén Ordóñez,
Michal Letek,
Noelia Valbuena,
José A. Gil,
Luís M. Mateos
Publication year - 2005
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.71.10.6206-6215.2005
Subject(s) - corynebacterium glutamicum , arsenite , operon , arsenate , biology , permease , mutant , gene , plasmid , biochemistry , genetics , microbiology and biotechnology , arsenic , chemistry , organic chemistry
Corynebacterium glutamicum is able to grow in media containing up to 12 mM arsenite and 500 mM arsenate and is one of the most arsenic-resistant microorganisms described to date. Two operons (ars1 andars2 ) involved in arsenate and arsenite resistance have been identified in the complete genome sequence ofCorynebacterium glutamicum . The operonsars1 andars2 are located some distance from each other in the bacterial chromosome, but they are both composed of genes encoding a regulatory protein (arsR ), an arsenite permease (arsB ), and an arsenate reductase (arsC ); operonars1 contains an additional arsenate reductase gene (arsC1′ ) located immediately downstream fromarsC1 . Additional arsenite permease and arsenate reductase genes (arsB3 andarsC4 ) scattered on the chromosome were also identified. The involvement ofars operons in arsenic resistance inC. glutamicum was confirmed by gene disruption experiments of the three arsenite permease genes present in its genome. Wild-type andarsB3 insertional mutantC. glutamicum strains were able to grow with up to 12 mM arsenite, whereasarsB1 andarsB2 C. glutamicum insertional mutants were resistant to 4 mM and 9 mM arsenite, respectively. The doublearsB1-arsB2 insertional mutant was resistant to only 0.4 mM arsenite and 10 mM arsenate. Gene amplification assays of operonsars1 andars2 inC. glutamicum revealed that the recombinant strains containing thears1 operon were resistant to up to 60 mM arsenite, this being one of the highest levels of bacterial resistance to arsenite so far described, whereas recombinant strains containing operonars2 were resistant to only 20 mM arsenite. Northern blot and reverse transcription-PCR analysis confirmed the presence of transcripts for all thears genes, the expression ofarsB3 andarsC4 being constitutive, and the expression ofarsR1 ,arsB1 ,arsC1 ,arsC1′ ,arsR2 ,arsB2 , andarsC2 being inducible by arsenite.