The nuclear actin-related protein Act3p/Arp4p of Saccharomyces cerevisiae is involved in transcription regulation of stress genes

Mol Microbiol. 2003 Nov;50(4):1155-71. doi: 10.1046/j.1365-2958.2003.03759.x.


A mutational analysis of the essential nuclear actin-related protein of Saccharomyces cerevisiae, Act3p/Arp4p, was performed. The five residues chosen for substitution were amino acids conserved between actin and Act3p/Arp4p, the tertiary structure of which most probably resembles that of actin. Two thermosensitive (ts) mutants, a single and a double point mutant, and one lethal double point mutant were obtained. Both ts mutants were formamide-sensitive which supports a structural relatedness of Act3p/Arp4p to actin; they were also hypersensitive against hydroxyurea and ultraviolet irradiation pointing to a possible role of Act3p/Arp4p in DNA replication and repair. Their 'suppressor of Ty' (SPT) phenotype, observed with another ts mutant of Act3p/Arp4p before, suggested involvement of Act3p/Arp4p in transcription regulation. Accordingly, genome-wide expression profiling revealed misregulated transcription in a ts mutant of a number of genes, among which increased expression of various stress-responsive genes (many of them requiring Msn2p/Msn4p for induction) was the most salient result. This provides an explanation for the mutant's enhanced resistance to severe thermal and oxidative stress. Thus, Act3p/Arp4p takes an important part in the repression of stress-induced genes under non-stress conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / genetics
  • Actins / metabolism*
  • Amino Acid Sequence
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Formamides / metabolism
  • Gene Expression Regulation, Fungal*
  • Heat-Shock Proteins / genetics*
  • Heat-Shock Proteins / metabolism
  • Hydroxyurea / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Nucleic Acid Synthesis Inhibitors / metabolism
  • Phenotype
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Sequence Alignment
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcription, Genetic*
  • Ultraviolet Rays


  • Actins
  • Arp4 protein, S cerevisiae
  • DNA-Binding Proteins
  • Formamides
  • Heat-Shock Proteins
  • MSN2 protein, S cerevisiae
  • Nuclear Proteins
  • Nucleic Acid Synthesis Inhibitors
  • Recombinant Fusion Proteins
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • formamide
  • Hydroxyurea