The modulation of the biological activities of mitochondrial histone Abf2p by yeast PKA and its possible role in the regulation of mitochondrial DNA content during glucose repression.
The mitochondrial histone, Abf2p, of Saccharomyces cerevisiae is essential for the maintenance of mitochondrial DNA (mtDNA) and appears to play an important role in the recombination and copy number determination of mtDNA. Abf2p, encoded by a nuclear gene, is a member of HMG1 DNA-binding protein family and has two HMG1-Box domains, HMG1-Box A and B. To investigate the role of Abf2p in the control of mtDNA copy number, we asked if the in vivo functions of Abf2p are regulated by the possible modification such as phosphorylation. We found that the N-terminal extended segment (KRPT(21)S(22)) of HMG1-Box A is rapidly and specifically phosphorylated by cAMP-dependent protein kinase (PKA) in vitro. The phosphorylation in this region inhibits the binding of Abf2p to all kinds of DNA including four-way junction DNA and the supercoiling activity of Abf2p itself. The abf2 mutant cells with an abf2(T21A/S22A) allele defective in the phosphorylation site have a severe defect in the regulation of mtDNA content during glucose repression in vivo. These observations suggest that the phosphorylation via PKA, that is activated during glucose repression, may regulate the in vivo functions of Abf2p for the control of mtDNA content during shift from gluconeogenic to fermentative growth.
Cho
J H
JH
Department of Life Science and Division of Molecular and Life Science, Pohang University of Science and Technology, 790-784, Pohang, South Korea.
Lee
Y K
YK
Chae
C B
CB
D000483:Alleles; D000595:Amino Acid Sequence; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004272:DNA, Mitochondrial / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D005786:Gene Expression Regulation; D005947:Glucose / Q000172:deficiency / Q000494:pharmacology; D024742:HMG-Box Domains; D024243:HMGB1 Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
C072843:ABF2 protein, S cerevisiae; D004272:DNA, Mitochondrial; D004268:DNA-Binding Proteins; D024243:HMGB1 Protein; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D017868:Cyclic AMP-Dependent Protein Kinases; D005947:Glucose