Functional characterization of the INO2 gene of Saccharomyces cerevisiae. A positive regulator of phospholipid biosynthesis

J Biol Chem. 1994 Mar 11;269(10):7402-11.

Abstract

The INO2 locus encodes a novel product showing structural similarity to the basic helix-loop-helix (b-HLH) family of regulatory proteins (Nikoloff, D.M., McGraw, P., and Henry, S.A. (1992) Nucleic Acids Res. 20, 3253). The ino2 mutants exhibit pleiotropic defects in phospholipid metabolism including inability to derepress the biosynthetic enzyme inositol-1-phosphate synthase. Localization of mutations in ino2 strains has demonstrated that the b-HLH domain is required for biological activity and is sensitive to perturbation, thereby establishing a correlation between the structure and function of Ino2p. Defects in the b-HLH domain of Ino2p resulted in reduced DNA binding activity. In addition, the absence of a specific DNA-protein complex correlated with a reduction or loss of INO1 transcription. Studies using Ino2p-specific antibody revealed that Ino2p participates in the formation of specific DNA-protein complexes. Ino2p-dependent binding activity overlapped with a region of the INO1 promoter that contains two potential HLH consensus binding sites. Furthermore, Ino2p showed single base pair discrimination in a putative binding site, establishing a relationship between Ino2p and its target binding site.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Basic Helix-Loop-Helix Transcription Factors
  • Binding Sites
  • DNA, Fungal
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Escherichia coli / genetics
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism
  • Helix-Loop-Helix Motifs
  • Molecular Sequence Data
  • Mutation
  • Phospholipids / biosynthesis*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Repressor Proteins*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins*
  • Transcription Factors*

Substances

  • Basic Helix-Loop-Helix Transcription Factors
  • DNA, Fungal
  • DNA-Binding Proteins
  • Fungal Proteins
  • INO2 protein, S cerevisiae
  • Phospholipids
  • Recombinant Fusion Proteins
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors