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Keywords:

Amino Acid Sequence, Arsenic Poisoning, Basic-Leucine Zipper Transcription Factors, Cloning, Molecular, DNA-Binding Proteins, Drug Resistance, Microbial, Fungal Proteins, Gene Amplification, Genes, Fungal, Molecular Sequence Data, Phenotype, Repressor Proteins, Restriction Mapping, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Homology, Amino Acid, 0605 Microbiology, 0699 Other Biological Sciences, 1003 Industrial Biotechnology, 3107 Microbiology

Abstract:

A 4.2 kb region from Saccharomyces cerevisiae chromosome XVI was isolated as a yeast fragment conferring resistance to 7 mM-sodium arsenite (NaAsO2), when put on a multicopy plasmid. Homology searches revealed a cluster of three new open reading frames named ACR1, ACR2 and ACR3. The hypothetical product of the ACR1 gene is similar to the transcriptional regulatory proteins, encoded by YAP1, and YAP2 genes from S. cerevisiae. Disruption of the ACR1 gene conduces to an arsenite and arsenate hypersensitivity phenotype. The ACR2 gene is indispensable for arsenate but not for arsenite resistance. The hypothetical product of the ACR3 gene shows high similarity to the hypothetical membrane protein encoded by Bacillus subtilis ORF1 of the skin element and weak similarity to the ArsB membrane protein of the Staphylococcus aureus arsenical-resistance operon. Overexpression of the ACR3 gene confers an arsenite- but not an arsenate-resistance phenotype. The presence of ACR3 together with ACR2 on a multicopy plasmid expands the resistance phenotype into arsenate. These findings suggest that all three novel genes: ACR1, ACR2 and ACR3 are involved in the arsenical-resistance phenomenon in S. cerevisiae.