| Summary: | [Eng] Fission yeast, Schizosaccharomyces pombe, represents a key model organism for studies of cell cycle regulation. Even though the biology of S. pombe is described to a great detail, certain aspects of crucial importance regarding cell cycle governing regulatory circuits are still unclear. In this study, we investigate a fission yeast CSL homologous transcription factor, Cbf11, the function of which is important for successful mitosis. Δcbf11 mutants are characterized by growth retardation and display a broad range of defects, of which we focus on catastrophic mitosis, also known as the cut (cell untimely torn) phenotype. We show the growth defects and the cut phenotype prevalence are conditional, being severe in Δcbf11 populations grown in the rich YES medium, but significantly less pronounced, when cultured in the minimal EMM medium. Our data indicate that the EMM-mediated cut phenotype rescue is caused by the excessive availability of nitrogen source (ammonium chloride in EMM), though we do not provide any molecular explanation. According to our data, mitotic defects observed in Δcbf11 mutants arise from transcriptional deregulation of lipid anabolism genes, cut6 and vht1, respectively encoding acetyl coenzyme A carboxylase and biotin transporter. Since Cut6 performance is biotin-dependent,...
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