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Gene Review

ABF2  -  Abf2p

Saccharomyces cerevisiae S288c

Synonyms: ARS-binding factor 2, mitochondrial, HIM1, YM9916.11, YMR072W
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Disease relevance of ABF2

  • After expression in Escherichia coli or purification from yeast mitochondria, two proteins were tested; they were ABF2 (a structural homologue of the human mitochondrial transcriptional activator mtTF1) and MTF1 (the gene product of a yeast locus known to exhibit a mitochondrial transcription phenotype) [1].
  • Recombinant ABF-2 exhibited potent microbicidal activity against Gram-positive and Gram-negative bacteria, and yeasts [2].

High impact information on ABF2

  • Two additional proteins known to function in mtDNA recombination, Abf2p and Mgt1p, are also required for parsing mtDNA into a larger number of nucleoids, although expression of these proteins is not under general amino acid control [3].
  • In zygotes lacking Abf2p, mtDNA sorting is delayed and preferential sorting is reduced [4].
  • A GFP-tagged form of Abf2p, a mtDNA binding protein required for faithful transmission of rho+ mtDNA in vegetatively growing cells, colocalizes with mtDNA in situ [4].
  • Moreover, in delta abf2 cells with a single copy of ILV5, changes in mtDNA stability correlate directly with changes in conditions that are known to affect ILV5 expression [5].
  • We have identified a multicopy suppressor of the mtDNA instability phenotype of cells with a null allele of the ABF2 gene (delta abf2) [5].

Biological context of ABF2

  • The yeast mitochondrial histone protein HM is required for maintenance of the mitochondrial genome, and disruption of the gene encoding HM (HIM1/ABF2) results in formation of a respiration-deficient petite mutant phenotype [6].
  • Analysis of an 11.7 kb DNA fragment of chromosome XI reveals a new tRNA gene and four new open reading frames including a leucine zipper protein and a homologue to the yeast mitochondrial regulator ABF2 [7].
  • This phenotype was partially rescued by malonic acid, indicating that reactive oxygen species generated by the electron transport chain contribute to mitochondrial dysfunction in abf2 Delta strains [8].
  • ABF2 interacts with DNA both nonspecifically and in a specific manner within regulatory regions, suggesting a mechanism whereby it may aid in compacting the mitochondrial genome without interfering with expression [9].
  • The predicted amino acid sequence of ABF2 is closely related to the high-mobility group proteins HMG1 and HMG2 from vertebrate cell nuclei and to several other DNA-binding proteins [9].

Anatomical context of ABF2

  • ABF2 (ARS-binding factor 2), a small, basic DNA-binding protein that binds specifically to the autonomously replicating sequence ARS1, is located primarily in the mitochondria of the yeast Saccharomyces cerevisiae [9].
  • Furthermore, a fused polypeptide containing only Dbf4 motifs M and C without any spacer can activate Hsk1 and is capable of rescuing the growth defect of him1 null cells [10].

Associations of ABF2 with chemical compounds

  • Overproduction of Abf2p by > or = 10-fold from an ABF2 gene placed under control of the GAL1 promoter, however, leads to a rapid loss of rho+ mtDNA and a quantitative conversion of rho+ cells to petites within two to four generations after a shift of the culture from glucose to galactose medium [11].
  • A mitochondrial HMG box protein, Abf2p, is needed for maintenance of mtDNA in cells grown on rich dextrose medium, but is dispensible in glycerol grown cells [12].

Regulatory relationships of ABF2

  • A sequence that is similar to the HMG DNA-binding domain is important for the DNA-binding activity of Yhm2p, and a mutation in this region abolishes the ability of YHM2 to suppress the temperature-sensitive defect of respiration of the abf2 null mutant [13].

Other interactions of ABF2

  • The most severe instability of rho+ mtDNA is observed in cells with null alleles of both ABF2 and ILV5 [5].
  • The results show that MTF1 specifies correct transcriptional initiation while ABF2 does not [1].
  • To better understand the role of Abf2p in the maintenance of the mitochondrial chromosome, we have isolated a multicopy suppressor (YHM2) of the temperature-sensitive defect associated with an abf2 null mutation [13].
  • Overexpression of MRPL40 did not prevent loss of mtDNA in a mutant strain lacking the mitochondrial protein Abf2p [14].
  • However, COXII and VAR1 sequences are 4-to 5-fold more sensitive to DNase I digestion of mtDNA in toluene-permeabilized mitochondria from the delta abf2 mutant than from wild-type cells, but no difference in DNase I sensitivity was detected with the ori5 probe [12].

Analytical, diagnostic and therapeutic context of ABF2

  • We used high-resolution atomic force microscopy to image the compaction of linear and circular DNA by the yeast mitochondrial protein Abf2p, which plays a major role in packaging mitochondrial DNA [15].
  • Immunoblotting with anti-Abf2p antibody demonstrated the association of Abf2p, a major mitochondrial DNA-binding protein, with the mt-nucleoids [16].


  1. Assignment of a yeast protein necessary for mitochondrial transcription initiation. Xu, B., Clayton, D.A. Nucleic Acids Res. (1992) [Pubmed]
  2. abf-1 and abf-2, ASABF-type antimicrobial peptide genes in Caenorhabditis elegans. Kato, Y., Aizawa, T., Hoshino, H., Kawano, K., Nitta, K., Zhang, H. Biochem. J. (2002) [Pubmed]
  3. The numbers of individual mitochondrial DNA molecules and mitochondrial DNA nucleoids in yeast are co-regulated by the general amino acid control pathway. MacAlpine, D.M., Perlman, P.S., Butow, R.A. EMBO J. (2000) [Pubmed]
  4. The sorting of mitochondrial DNA and mitochondrial proteins in zygotes: preferential transmission of mitochondrial DNA to the medial bud. Okamoto, K., Perlman, P.S., Butow, R.A. J. Cell Biol. (1998) [Pubmed]
  5. An enzyme in yeast mitochondria that catalyzes a step in branched-chain amino acid biosynthesis also functions in mitochondrial DNA stability. Zelenaya-Troitskaya, O., Perlman, P.S., Butow, R.A. EMBO J. (1995) [Pubmed]
  6. Essential role of the HMG domain in the function of yeast mitochondrial histone HM: functional complementation of HM by the nuclear nonhistone protein NHP6A. Kao, L.R., Megraw, T.L., Chae, C.B. Proc. Natl. Acad. Sci. U.S.A. (1993) [Pubmed]
  7. Analysis of an 11.7 kb DNA fragment of chromosome XI reveals a new tRNA gene and four new open reading frames including a leucine zipper protein and a homologue to the yeast mitochondrial regulator ABF2. Purnelle, B., Skala, J., van Dyck, L., Goffeau, A. Yeast (1994) [Pubmed]
  8. Mitochondrial dysfunction due to oxidative mitochondrial DNA damage is reduced through cooperative actions of diverse proteins. O'Rourke, T.W., Doudican, N.A., Mackereth, M.D., Doetsch, P.W., Shadel, G.S. Mol. Cell. Biol. (2002) [Pubmed]
  9. A close relative of the nuclear, chromosomal high-mobility group protein HMG1 in yeast mitochondria. Diffley, J.F., Stillman, B. Proc. Natl. Acad. Sci. U.S.A. (1991) [Pubmed]
  10. Bipartite binding of a kinase activator activates Cdc7-related kinase essential for S phase. Ogino, K., Takeda, T., Matsui, E., Iiyama, H., Taniyama, C., Arai , K., Masai, H. J. Biol. Chem. (2001) [Pubmed]
  11. Functions of the high mobility group protein, Abf2p, in mitochondrial DNA segregation, recombination and copy number in Saccharomyces cerevisiae. Zelenaya-Troitskaya, O., Newman, S.M., Okamoto, K., Perlman, P.S., Butow, R.A. Genetics (1998) [Pubmed]
  12. Analysis of mitochondrial DNA nucleoids in wild-type and a mutant strain of Saccharomyces cerevisiae that lacks the mitochondrial HMG box protein Abf2p. Newman, S.M., Zelenaya-Troitskaya, O., Perlman, P.S., Butow, R.A. Nucleic Acids Res. (1996) [Pubmed]
  13. A novel DNA-binding protein bound to the mitochondrial inner membrane restores the null mutation of mitochondrial histone Abf2p in Saccharomyces cerevisiae. Cho, J.H., Ha, S.J., Kao, L.R., Megraw, T.L., Chae, C.B. Mol. Cell. Biol. (1998) [Pubmed]
  14. High levels of the mitochondrial large ribosomal subunit protein 40 prevent loss of mitochondrial DNA in null mmf1 Saccharomyces cerevisiae cells. Accardi, R., Oxelmark, E., Jauniaux, N., de Pinto, V., Marchini, A., Tommasino, M. Yeast (2004) [Pubmed]
  15. Mechanism of DNA compaction by yeast mitochondrial protein Abf2p. Friddle, R.W., Klare, J.E., Martin, S.S., Corzett, M., Balhorn, R., Baldwin, E.P., Baskin, R.J., Noy, A. Biophys. J. (2004) [Pubmed]
  16. Identification of the YMN-1 antigen protein and biochemical analyses of protein components in the mitochondrial nucleoid fraction of the yeast Saccharomyces cerevisiae. Sato, H., Tachifuji, A., Tamura, M., Miyakawa, I. Protoplasma (2002) [Pubmed]
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