Cytochrome c methyltransferase, Ctm1p, of yeast.

TitleCytochrome c methyltransferase, Ctm1p, of yeast.
Publication TypeJournal Article
Year of Publication2000
AuthorsPolevoda, B, Martzen, MR, Das, B, Phizicky, EM, Sherman, F
JournalJ Biol Chem
Date Published2000 Jul 07
KeywordsAmino Acid Sequence, Amino Acids, Apoproteins, Base Sequence, Cell Fractionation, Cytochrome c Group, Cytochromes c, Cytosol, Fungal Proteins, Histone-Lysine N-Methyltransferase, Lysine, Methylation, Molecular Sequence Data, Mutation, RNA, Messenger, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Alignment, Spectrophotometry

Cytochromes c from plants and fungi, but not higher animals, contain methylated lysine residues at specific positions, including for example, the trimethylated lysine at position 72 in iso-1-cytochrome c of the yeast Saccharomyces cerevisiae. Testing of 6,144 strains of S. cerevisiae, each overproducing a different open reading frame fused to glutathione S-transferase, previously revealed that YHR109w was associated with an activity that methylated horse cytochrome c. We show here that this open reading frame, denoted Ctm1p, is specifically responsible for trimethylating lysine 72 of iso-1-cytochrome c. Unmethylated forms of cytochrome c but not other proteins or nucleic acids are methylated in vitro by Ctm1p produced in S. cerevisiae or Escherichia coli. Iso-1-cytochrome c purified from a ctm1-Delta strain is not trimethylated in vivo, whereas the K72R mutant form, or the trimethylated Lys-72 form of iso-1-cytochrome c, are not significantly methylated by Ctm1p in vitro. Like apocytochrome c, but in contrast to holocytochrome c, Ctm lp is located in the cytosol, consistent with the view that the natural substrate is apocytochrome c. The ctm1-Delta strain lacking the methyltransferase did not exhibit any growth defect on a variety of media and growth conditions, and the unmethylated iso-1-cytochrome c was produced at the normal level and exhibited the normal activity in vivo. Ctm1p and cytochrome c were coordinately regulated during anaerobic to aerobic transition, a finding consistent with the view that this methyltransferase evolved to act on cytochrome c.

Alternate JournalJ. Biol. Chem.
Citation Key10.1074/jbc.M001891200
PubMed ID10791961
Grant ListGM12702 / GM / NIGMS NIH HHS / United States