In yeast, the genes COX5a and COX5b encode structurally divergent, yet functionally interchangeable forms of subunit V of cytochrome c oxidase, a mitochondrial inner membrane protein complex. A form of this subunit, either Va or Vb, is required for cytochrome oxidase activity, and hence, for cellular respiration. In yeast cells, these genes are not expressed at equivalent levels; they are normally regulated in opposite ways at the level of transcription. This regulation leads to markedly different intracellular levels of subunits Va and Vb. We propose to continue, and to expand our work on the biology and regulation of the yeast COX5 genes. We will study, in detail, the molecular mechanisms that underlie the transcriptional regulation of these genes. In particular, we will focus on understanding how oxygen and heme exert an inverse effect on COX5 expression. This will be accomplished using a combined molecular, biochemical, and genetic approach. Using deletion, linker insertion, and site directed mutagenesis, we will continue to define the cis-acting elements involved in the transcription of the COX5a and COX5b genes. Using biochemical techniques, including gel-retardation assays and DNA footprinting, we will identify the trans-acting factors that interact with those specific regulatory sites. Using regulatory mutants, in conjunction with the biochemical assays already mentioned, we will identify and isolate the genes whose products are involved in COX5 expression. If successful, these studies will lead to a clear understanding of the regulation of the COX5 gene family. As such, they will contribute important insights into our overall knowledge of gene expression, of nuclear mitochondrial interactions, and of mitochondrial biogenesis.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM036675-07
Application #
3291112
Study Section
Molecular Biology Study Section (MBY)
Project Start
1986-04-01
Project End
1994-03-31
Budget Start
1992-04-01
Budget End
1993-03-31
Support Year
7
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of California Irvine
Department
Type
Schools of Arts and Sciences
DUNS #
161202122
City
Irvine
State
CA
Country
United States
Zip Code
92697
Gaikwad, A S; Cumsky, M G (1994) The use of chemical cross-linking to identify proteins that interact with a mitochondrial presequence. J Biol Chem 269:6437-43
Miller, B R; Cumsky, M G (1993) Intramitochondrial sorting of the precursor to yeast cytochrome c oxidase subunit Va. J Cell Biol 121:1021-9
Miller, B R; Cumsky, M G (1991) An unusual mitochondrial import pathway for the precursor to yeast cytochrome c oxidase subunit Va. J Cell Biol 112:833-41
Hodge, M R; Singh, K; Cumsky, M G (1990) Upstream activation and repression elements control transcription of the yeast COX5b gene. Mol Cell Biol 10:5510-20
Glaser, S M; Miller, B R; Cumsky, M G (1990) Removal of a hydrophobic domain within the mature portion of a mitochondrial inner membrane protein causes its mislocalization to the matrix. Mol Cell Biol 10:1873-81
Glaser, S M; Cumsky, M G (1990) A synthetic presequence reversibly inhibits protein import into yeast mitochondria. J Biol Chem 265:8808-16
Glaser, S M; Cumsky, M G (1990) Localization of a synthetic presequence that blocks protein import into mitochondria. J Biol Chem 265:8817-22
Hodge, M R; Cumsky, M G (1989) Splicing of a yeast intron containing an unusual 5' junction sequence. Mol Cell Biol 9:2765-70
Hodge, M R; Kim, G; Singh, K et al. (1989) Inverse regulation of the yeast COX5 genes by oxygen and heme. Mol Cell Biol 9:1958-64
Glaser, S M; Trueblood, C E; Dircks, L K et al. (1988) Functional analysis of mitochondrial protein import in yeast. J Cell Biochem 36:275-87