title: The involvement of the Schizosaccharomyces pombe sep9/spt8 gene in the regulation of septum cleavage.
abstract: Schizosaccharomyces cells divide by medial septation, followed by enzymatic degradation of parts of the septum (septum cleavage) to allow the sister cells to separate from each other. In a previous study we found that the cell separation mutant sep9-307 was defective in a gene that encodes a protein highly similar in sequence to the Saccharomyces cerevisiae protein Spt8, a subunit of the SAGA complex. Here, we show that the sep9-307 mutation causes a frameshift in translation. The deletion of sep9(+) is not lethal but abolishes normal septum cleavage by reducing the activity of ace2(+), a gene coding for a transcription factor of numerous genes producing proteins for septum cleavage. Indirect evidence indicates that Sep9 might also act directly in the transcription of certain target genes (e.g. eng1(+)) of this regulator. sep9-307 is synthetically lethal with mutations in the cell separation genes sep11/med18(+) and sep15/med8(+), which encode subunits of the general transcription factor mediator. Heterologous expression of SPT8 and the putative Schizosaccharomyces japonicus sep9(+) orthologue cannot substitute for sep9(+). Both Spt8 and the fission yeast proteins have highly acidic (74-76 amino-acid long) N-terminal regions with no sequence conservation.
authors.affiliation: Department of Genetics and Applied Microbiology, University of Debrecen, Debrecen, Hungary.
authors.forename: Gyula
authors.initials: G
authors.lastname: Batta
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Szilagyi
authors.forename: Miklos
authors.initials: M
authors.lastname: Laczik
authors.forename: Matthias
authors.initials: M
authors.lastname: Sipiczki
mesh_terms: D002455:Cell Division; D016368:Frameshift Mutation; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D020043:Genes, Essential; D050296:Microbial Viability; D010802:Phylogeny; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D012568:Schizosaccharomyces / Q000254:growth & development / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics
chemical_list: D005656:Fungal Proteins; C089445:SPT8 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors