The product of the SNF2/SWI2 paralogue INO80 of Saccharomyces cerevisiae required for efficient expression of various yeast structural genes is part of a high-molecular-weight protein complex
R. Ebbert et al., The product of the SNF2/SWI2 paralogue INO80 of Saccharomyces cerevisiae required for efficient expression of various yeast structural genes is part of a high-molecular-weight protein complex, MOL MICROB, 32(4), 1999, pp. 741-751
Structural genes of phospholipid biosynthesis in the yeast Saccharomyces ce
revisiae are activated by the Ino2p/Ino4p transcription factor that binds t
o ICRE promoter motifs and mediates maximal gene expression in the absence
of inositol. We identified the ino80 mutation causing inositol auxotrophy a
s a result of a defect in ICRE-dependent gene activation. The product of th
e corresponding wild-type gene INO80 (= YGL150C) shows significant similari
ty to the Snf2p family of DNA-dependent ATPases, Nevertheless, SNF2 in incr
eased gene dosage did not suppress ino80 mutant phenotypes, Mutation of the
Ino80p lysine residue corresponding to the NTP binding site of Snf2p led t
o a non-functional protein, In ino80 null mutants, gene activation mediated
by an ICRE decreased to 16% of the wild-type level, Maximal expression of
PHO5, GAL1, CYC1 and ICL1 was also significantly reduced, Thus, Ino80p affe
cts several transcription factors involved in unrelated pathways, As demons
trated by gel filtration, Ino80p is part of a high-molecular-weight complex
of more than 1 MDa. Similar to what was found for Snf2p, the Ino80p-contai
ning complex may influence the transcriptional level of several unrelated s
tructural genes by functioning as an ATPase that possibly acts on chromatin
.