Open AccessOxygen sensing in yeast: Evidence for the involvement of the respiratory chain in regulating the transcription of a subset of hypoxic genes
Author(s) -
Kurt E. Kwast,
Patricia V. Burke,
Brett T. Staahl,
Robert O. Poyton
Publication year - 1999
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.96.10.5446
Subject(s) - biology , yeast , hemeprotein , mutant , cytochrome c oxidase , biochemistry , gene , gene expression , heme , respiratory chain , transcription factor , cytochrome , microbiology and biotechnology , enzyme
Oxygen availability affects the transcription of a number of genes in nearly all organisms. Although the molecular mechanisms for sensing oxygen are not precisely known, heme is thought to play a pivotal role. Here, we address the possibility that oxygen sensing in yeast, as in mammals, involves a redox-sensitive hemoprotein. We have found that carbon monoxide (CO) completely blocks the anoxia-induced expression of two hypoxic genes,OLE1 andCYC7 , partially blocks the induction of a third gene, COX5b , and has no effect on the expression of other hypoxic or aerobic genes. In addition, transition metals (Co and Ni) induce the expression ofOLE1 andCYC7 in a concentration-dependent manner under aerobic conditions. These findings suggest that the redox state of an oxygen-binding hemoprotein is involved in controlling the expression of at least two hypoxic yeast genes. By using mutants deficient in each of the two major yeast CO-binding hemoproteins (cytochromec oxidase and flavohemoglobin), respiratory inhibitors, andcob1 and ρ0 mutants, we have found that the respiratory chain is involved in the anoxic induction of these two genes and that cytochromec oxidase is likely the hemoprotein “sensor.” Our findings also indicate that there are at least two classes of hypoxic genes in yeast (CO sensitive and CO insensitive) and imply that multiple pathways/mechanisms are involved in modulating the expression of hypoxic yeast genes.