Two conserved modules of Schizosaccharomyces pombe Mediator regulate distinct cellular pathways.
Mediator is an evolutionary conserved coregulator complex required for transcription of almost all RNA polymerase II-dependent genes. The Schizosaccharomyces pombe Mediator consists of two dissociable components-a core complex organized into a head and middle domain as well as the Cdk8 regulatory subcomplex. In this work we describe a functional characterization of the S. pombe Mediator. We report the identification of the S. pombe Med20 head subunit and the isolation of ts alleles of the core head subunit encoding med17+. Biochemical analysis of med8(ts), med17(ts), Deltamed18, Deltamed20 and Deltamed27 alleles revealed a stepwise head domain molecular architecture. Phenotypical analysis of Cdk8 and head module alleles including expression profiling classified the Mediator mutant alleles into one of two groups. Cdk8 module mutants flocculate due to overexpression of adhesive cell-surface proteins. Head domain-associated mutants display a hyphal growth phenotype due to defective expression of factors required for cell separation regulated by transcription factor Ace2. Comparison with Saccharomyces cerevisiae Mediator expression data reveals that these functionally distinct modules are conserved between S. pombe and S. cerevisiae.
Linder
Tomas
T
Division of Metabolic Diseases, Karolinska Institutet, Novum, SE-141 86 Stockholm, Sweden. tlinder@cmp.ucsf.edu
Rasmussen
Nina N
NN
Samuelsen
Camilla O
CO
Chatzidaki
Emmanouella
E
Baraznenok
Vera
V
Beve
Jenny
J
Henriksen
Peter
P
Gustafsson
Claes M
CM
Holmberg
Steen
S
D000483:Alleles; D002473:Cell Wall / Q000378:metabolism; D056850:Cyclin-Dependent Kinase 8; D018844:Cyclin-Dependent Kinases / Q000235:genetics; D020869:Gene Expression Profiling; D009154:Mutation; D010641:Phenotype; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
D021122:Protein Subunits; D029702:Schizosaccharomyces pombe Proteins; D015534:Trans-Activators; D056850:Cyclin-Dependent Kinase 8; D018844:Cyclin-Dependent Kinases; C112462:srb10 protein, S pombe