Rtg3p, a basic helix-loop-helix/leucine zipper protein that functions in mitochondrial-induced changes in gene expression, contains independent activation domains

Beverly A. Rothermel, Janet L. Thornton, Ronald A. Butow

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

Rtg3p and Rtg1p are basic helix-loop-helix/leucine zipper protein transcription factors in yeast that interact and bind to sites in an upstream activation sequence element in the 5'-flanking region of CIT2, a gene encoding a peroxisomal isoform of citrate synthase. These factors are required both for basal expression of CIT2 and its elevated expression in cells with dysfunctional mitochondria, such as in respiratory-deficient petite cells lacking mitochondrial DNA (ρ°). This elevated expression of CIT2 is called the retrograde response. Here we show that fusion constructs between the Gal4p DNA binding domain and Rtg3p transactivate the expression of a LacZ reporter gene under the control of a GAL1 promoter element. We have identified two activation domains in Rtg3p: a strong carboxyl-terminal domain from amino acids 375-486, and a weaker amino-terminal domain from amino acids 1-175: neither of these activation domains contain the bHLH/Zip motif. We have also identified a serine/threonine-rich domain of Rtg3p within amino acids 176-282 that is inhibitory to transactivation. In addition, the transcriptional activity of the Gal4-Rtg3p fusion proteins does not require either Rtg1p or Rtg2p; the latter is a protein containing an hsp70-like ATP binding domain that is also necessary for CIT2 expression. In contrast, transcriptional activation by Gal4-Rtg1p fusion proteins requires the Rtg1p basic helix-loop-helix/leucine zipper protein domain, as well as Rtg3p and Rtg2p. These data suggest that transcriptional activation by the Rtg1p-Rtg3p complex is largely the function of Rtg3p. Experiments are also presented suggesting that Rtg3p is limiting for gene expression in respiratory- competent (ρ+) cells.

Original languageEnglish (US)
Pages (from-to)19801-19807
Number of pages7
JournalJournal of Biological Chemistry
Volume272
Issue number32
DOIs
StatePublished - Aug 8 1997

Fingerprint

Leucine Zippers
Gene expression
Chemical activation
Transcriptional Activation
Gene Expression
Amino Acids
Fusion reactions
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
Proteins
Citrate (si)-Synthase
Lac Operon
5' Flanking Region
Threonine
Mitochondrial DNA
Reporter Genes
Mitochondria
Gene encoding
Serine
Protein Isoforms
Adenosine Triphosphate

ASJC Scopus subject areas

  • Biochemistry

Cite this

Rtg3p, a basic helix-loop-helix/leucine zipper protein that functions in mitochondrial-induced changes in gene expression, contains independent activation domains. / Rothermel, Beverly A.; Thornton, Janet L.; Butow, Ronald A.

In: Journal of Biological Chemistry, Vol. 272, No. 32, 08.08.1997, p. 19801-19807.

Research output: Contribution to journalArticle

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