Ume6 is required for the MATa/MATα cellular identity and transcriptional silencing in Kluyveromyces lactis
2010 (English)In: Genetics, ISSN 0016-6731, E-ISSN 1943-2631, Vol. 184, no 4, 999-1011 p.Article in journal (Refereed) Published
To explore the similarities and differences of regulatory circuits among budding yeasts, we characterized the role of the unscheduled meiotic gene expression 6 (UME6) gene in Kluyveromyces lactis. We found that Ume6 was required for transcriptional silencing of the cryptic mating-type loci HMLα and HMRa. Chromatin immunoprecipitation (ChIP) suggested that Ume6 acted directly by binding the cis-regulatory silencers of these loci. Unexpectedly, a MATa ume6 strain was mating proficient, whereas a MATα ume6 strain was sterile. This observation was explained by the fact that ume6 derepressed HMLα2 only weakly, but derepressed HMRa1 strongly. Consistently, two a/α-repressed genes (MTS1 and STE4) were repressed in the MATα ume6 strain, but were expressed in the MATa ume6 strain. Surprisingly, ume6 partially suppressed the mating defect of a MATa sir2 strain. MTS1 and STE4 were repressed in the MATa sir2 ume6 double-mutant strain, indicating that the suppression acted downstream of the a1/α2-repressor. We show that both STE12 and the MATa2/HMRa2 genes were overexpressed in the MATa sir2 ume6 strain. Consistent with the idea that this deregulation suppressed the mating defect, ectopic overexpression of Ste12 and a2 in a MATa sir2 strain resulted in efficient mating. In addition, Ume6 served as a block to polyploidy, since ume6/ume6 diploids mated as pseudo a-strains. Finally, Ume6 was required for repression of three meiotic genes, independently of the Rpd3 and Sin3 corepressors.
Place, publisher, year, edition, pages
The Genetics Society of America , 2010. Vol. 184, no 4, 999-1011 p.
Ume6, transcriptional scilencing, K. lactis, Mts1, Ste4, Sir2
Research subject Zoological Developmental Biology
IdentifiersURN: urn:nbn:se:su:diva-42002DOI: 10.1534/genetics.110.114678ISI: 000281889000010PubMedID: 20139343OAI: oai:DiVA.org:su-42002DiVA: diva2:343505