title: Ask10p mediates the oxidative stress-induced destruction of the Saccharomyces cerevisiae C-type cyclin Ume3p/Srb11p.
abstract: Srb11p-Srb10p is the budding yeast C-type cyclin-cyclin-dependent kinase that is required for the repression of several stress response genes. To relieve this repression, Srb11p is destroyed in cells exposed to stressors, including heat shock and oxidative stress. In the present study, we identified Ask10p (for activator of Skn7) by two-hybrid analysis as an interactor with Srb11p. Coimmunoprecipitation studies confirmed this association, and we found that, similar to Srb11p-Srb10p, Ask10p is a component of the RNA polymerase II holoenzyme. Ask10p is required for Srb11p destruction in response to oxidative stress but not heat shock. Moreover, this destruction is important since the hypersensitivity of an ask10 mutant strain to oxidative stress is rescued by deleting SRB11. We further show that Ask10p is phosphorylated in response to oxidative stress but not heat shock. This modification requires the redundant mitogen-activated protein (MAP) kinase kinase Mkk1/2 but not their normal MAP kinase target Slt2p. Moreover, the other vegetative MAP kinases--Hog1p, Fus3p, or Kss1p--are not required for Ask10p phosphorylation, suggesting the existence of an alternative pathway for transducing the Pkc1p-->Bck1-->Mkk1/2 oxidative stress signal. In conclusion, Ask10p is a new component of the RNA polymerase II holoenzyme and an important regulator of the oxidative stress response. In addition, these results define a new role for the Pkc1p MAP kinase cascade (except the MAP kinase itself) in transducing the oxidative damage signal directly to the RNA polymerase II holoenzyme, thereby bypassing the stress-activated transcription factors.
authors.affiliation: Department of Molecular Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Cohen
authors.forename: Kun
authors.initials: K
authors.lastname: Lee
authors.forename: Lisa H
authors.initials: LH
authors.lastname: Rutkowski
authors.forename: Randy
authors.initials: R
authors.lastname: Strich
mesh_terms: D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016213:Cyclins; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D018869:Heat-Shock Response; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D018384:Oxidative Stress / Q000502:physiology*; D010766:Phosphorylation; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D020798:Two-Hybrid System Techniques
chemical_list: C487632:Ask10 protein, S cerevisiae; D016213:Cyclins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D006861:Hydrogen Peroxide; C093345:SSN8 protein, S cerevisiae; D018844:Cyclin-Dependent Kinases; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D012321:DNA-Directed RNA Polymerases