Irniger, Stefan

[["dc.bibliographiccitation.firstpage","31"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Journal of Molecular Biology"],["dc.bibliographiccitation.lastpage","43"],["dc.bibliographiccitation.volume","378"],["dc.contributor.author","Sari, Fatih"],["dc.contributor.author","Heinrich, Melanie"],["dc.contributor.author","Meyeri, Wibke"],["dc.contributor.author","Braus, Gerhard H."],["dc.contributor.author","Irniger, Stefan"],["dc.date.accessioned","2018-11-07T11:16:02Z"],["dc.date.available","2018-11-07T11:16:02Z"],["dc.date.issued","2008"],["dc.description.abstract","The cyclin-dependent kinase CdkI and the related kinase Ime2 act in concert to trigger progression of the meiotic cell cycle in the yeast Saccharomyces cerevisiae. These kinases share several functions and substrates during meiosis, but their regulation seems to be clearly different. In contrast to Cdk1, no cyclin seems to be involved in the regulation of Ime2 activity. Ime2 is a highly unstable protein, and we aimed to elucidate the relevance of Ime2 instability. We first determined the sequence elements required for Ime2 instability by constructing a set of deletions in the IME2 gene. None of the small deletions in Ime2 affected its instability but deletion of a 241 amino acid C-terminal region resulted in a highly stabilized protein. Thus, the C-terminal domain of Ime2 is important for mediating protein instability. The stabilized, truncated Ime2 protein is highly active in vivo. Replacement of the IME2 gene with the truncated IME2 Delta C241 in diploid strains did not interfere with meiotic nuclear divisions, but caused abnormalities in spore formation, as manifested by the appearance of many asci with a reduced spore number such as triads and dyads. The truncated Ime2 caused a reduction of spore number in a dominant manner. We conclude that downregulation of Ime2 kinase activity mediated by the C-terminal domain is required for the efficient production of normal four-spore asci. Our data suggest a role for Ime2 in spore number control in S. cerevisiae."],["dc.identifier.doi","10.1016/j.jmb.2008.02.001"],["dc.identifier.isi","000255368200004"],["dc.identifier.pmid","18339400"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/54501"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Academic Press Ltd- Elsevier Science Ltd"],["dc.relation.issn","1089-8638"],["dc.relation.issn","0022-2836"],["dc.title","The C-terminal region of the meiosis-specific protein kinase Ime2 mediates protein instability and is required for normal spore formation in budding yeast"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1278"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","Molecular Microbiology"],["dc.bibliographiccitation.lastpage","1295"],["dc.bibliographiccitation.volume","71"],["dc.contributor.author","Bayram, Oezguer"],["dc.contributor.author","Sari, Fatih"],["dc.contributor.author","Braus, Gerhard H."],["dc.contributor.author","Irniger, Stefan"],["dc.date.accessioned","2018-11-07T08:32:21Z"],["dc.date.available","2018-11-07T08:32:21Z"],["dc.date.issued","2009"],["dc.description.abstract","Spore formation is a common process in the developmental cycle of fungi. In the yeast Saccharomyces cerevisiae, Ime2 is a key protein kinase for the meiotic cell cycle, which precedes ascospore formation. Here, we analysed the IME2-related imeB gene of the filamentous ascomycete Aspergillus nidulans. imeB deletion strains are retarded in growth and overproduce fertile sexual fruiting bodies in the presence of light, which normally represses sexual development. imeB mutants also display abnormal differentiation of sexual Hulle cells in submerged cultures. Increased sexual development of imeB mutants is dependent on VeA, a component of the heterotrimeric velvet complex. A combined deletion of imeB with the phytochrome fphA, a red light receptor, results in a complete loss of light response, suggesting that ImeB and FphA cooperate in light-mediated inhibition of sexual development. Furthermore, we found that imeB mutants fail to produce the mycotoxin sterigmatocystin, an aflatoxin precursor, and show that ImeB is needed for expression of the sterigmatocystin gene cluster. ImeB contains a TXY motif conserved in mitogen-activated protein kinases. This sequence element is essential for ImeB function. We conclude that ImeB is a mitogen-activated protein kinase-related protein kinase required for the co-ordinated control of light-dependent development with mycotoxin production."],["dc.identifier.doi","10.1111/j.1365-2958.2009.06606.x"],["dc.identifier.isi","000263522000017"],["dc.identifier.pmid","19210625"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/17324"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-blackwell Publishing, Inc"],["dc.relation.issn","0950-382X"],["dc.title","The protein kinase ImeB is required for light-mediated inhibition of sexual development and for mycotoxin production in Aspergillus nidulans"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2611"],["dc.bibliographiccitation.issue","13"],["dc.bibliographiccitation.journal","Cell Cycle"],["dc.bibliographiccitation.lastpage","2619"],["dc.bibliographiccitation.volume","9"],["dc.contributor.author","Kuczera, Tanja"],["dc.contributor.author","Bayram, Oezguer"],["dc.contributor.author","Sari, Fatih"],["dc.contributor.author","Braus, Gerhard H."],["dc.contributor.author","Irniger, Stefan"],["dc.date.accessioned","2018-11-07T08:41:34Z"],["dc.date.available","2018-11-07T08:41:34Z"],["dc.date.issued","2010"],["dc.description.abstract","Progression through mitosis requires the activity of cyclin-dependent kinases (CDKs) associated with regulatory cyclin subunits. In the yeast Saccharomyces cerevisiae, Clb2 has the most important role among the four mitotic cyclins, Clb1-4, manifested by data showing that simultaneous deletion of the CLB1, CLB3 and CLB4 genes has only minor effects on mitosis. Thus, Clb2 alone is sufficient for all essential CDK functions in mitosis, such as the assembly of bipolar spindles and spindle elongation. Here, we show that a modification of Clb2, by the C-terminal addition of a Myc12 epitope, causes the loss of one specific mitotic function of Clb2. Strains carrying CLB2-MYC12 are nonviable in the absence of the CLB3 and CLB4 genes, because the modified Clb2 version fails to promote assembly of the mitotic spindle. In contrast, Clb2-Myc12 has no apparent defects in late mitotic functions and, furthermore, induces the switch from polarized to isotropic growth with similar efficiency as the endogenous Clb2. Thus, the presence of the Myc12 epitope selectively inactivates Clb2's capacity to promote spindle formation. Clb2-Myc12 represents therefore the first version of Clb2 impaired in one specific mitotic function. We conclude that the major mitotic functions of this cyclin can be unequivocally dissected."],["dc.identifier.doi","10.4161/cc.9.13.12082"],["dc.identifier.isi","000281205400035"],["dc.identifier.pmid","20581451"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/19497"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Taylor & Francis Inc"],["dc.relation.issn","1551-4005"],["dc.relation.issn","1538-4101"],["dc.title","Dissection of mitotic functions of the yeast cyclin Clb2"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","26614"],["dc.bibliographiccitation.issue","36"],["dc.bibliographiccitation.journal","Journal of Biological Chemistry"],["dc.bibliographiccitation.volume","282"],["dc.contributor.author","Sari, Fatih"],["dc.contributor.author","Braus, Gerhard H."],["dc.contributor.author","Irniger, Stefan"],["dc.date.accessioned","2018-11-07T10:58:38Z"],["dc.date.available","2018-11-07T10:58:38Z"],["dc.date.issued","2007"],["dc.description.abstract","Proteolytic destruction of many cyclins is induced by a multisubunit ubiquitin ligase termed the anaphase promoting complex/ cyclosome (APC/C). In the budding yeast Saccharomyces cerevisiae, the S phase cyclin Clb5 and the mitotic cyclins Clb1-4 are known as substrates of this complex. The relevance of APC/C in proteolysis of Clb5 is still under debate. Importantly, a deletion of the Clb5 destruction box has little influence on cell cycle progression. To understand Clb5 degradation in more detail, we applied in vivo pulse labeling to determine the half-life of Clb5 at different cell cycle stages and in the presence or absence of APC/C activity. Clb5 is significantly unstable, with a half-life of similar to 8-10 min, at cell cycle periods when APC/C is inactive and in mutants impaired in APC/C function. A Clb5 version lacking its cyclin destruction box is similarly unstable. The half-life of Clb5 is further decreased in a destruction box-dependent manner to 3-5 min in mitotic or G(1) cells with active APC/C. Clb5 instability is highly dependent on the function of the proteasome. We conclude that Clb5 proteolysis involves two different modes for targeting of Clb5 to the proteasome, an APC/C-dependent and an APC/C-independent mechanism. These different modes apparently have overlapping functions in restricting Clb5 levels in a normal cell cycle, but APC/C function is essential in the presence of abnormally high Clb5 levels."],["dc.identifier.doi","10.1074/jbc.M703744200"],["dc.identifier.isi","000249239600064"],["dc.identifier.pmid","17620341"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/50508"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Soc Biochemistry Molecular Biology Inc"],["dc.relation.issn","1083-351X"],["dc.relation.issn","0021-9258"],["dc.title","A process independent of the anaphase-promoting complex contributes to instability of the yeast S phase cyclin Clb5"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]