Two zinc-cluster transcription factors control induction of alternative oxidase in Neurospora crassa.
The alternative oxidase transfers electrons from ubiquinol to molecular oxygen, providing a mechanism for bypassing the later steps of the standard cytochrome-mediated electron transport chain. The enzyme is found in an array of organisms and in many cases is known to be produced in response to perturbations of the standard chain. Alternative oxidase is encoded in the nucleus but functions in the inner mitochondrial membrane. This implies the existence of a retrograde regulation pathway for communicating from the mitochondrion to the nucleus to induce alternative oxidase expression. Previous studies on alternative oxidase in fungi and plants have shown that a number of genes are required for expression of the enzyme, but the identity of these genes has remained elusive. By gene rescue we have now shown that the aod-2 and aod-5 genes of Neurospora crassa encode transcription factors of the zinc-cluster family. Electrophoretic mobility shift assays show that the DNA-binding domains of the AOD2 and AOD5 proteins act in tandem to bind a sequence element in the alternative oxidase gene promoter that is required for expression. Both proteins contain potential PAS domains near their C terminus, which are found primarily in proteins involved in signal transduction.
Chae
Michael S
MS
Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
Nargang
Cheryl E
CE
Cleary
Ian A
IA
Lin
Colin C
CC
Todd
Andrea T
AT
Nargang
Frank E
FE
D001665:Binding Sites; D004579:Electron Transport; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D024101:Mitochondrial Proteins; D009492:Neurospora crassa / Q000201:enzymology*; D010088:Oxidoreductases / Q000235:genetics*; D010940:Plant Proteins; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D014157:Transcription Factors; D015032:Zinc; D000099188:Alternative Oxidase
D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D014157:Transcription Factors; D015032:Zinc; D000099188:Alternative Oxidase