LAMMER Kinase Lkh1 Is an Upstream Regulator of Prk1-Mediated Non-Sexual Flocculation in Fission Yeast

The cation-dependent galactose-specific flocculation activity of the Schizosaccharomyces pombe null mutant of lkh1þ, the gene encoding LAMMER kinase homolog, has previously been reported by our group. Here, we show that disruption of prk1þ, another flocculation associated regulatory kinase encoding gene, also resulted in cation-dependent galactose-specific flocculation. Deletion of prk1 increased the flocculation phenotype of the lkh1þ null mutant and its overexpression reversed the flocculation of cells caused by lkh1 deletion. Transcript levels of prk1þ were also decreased by lkh1þ deletion. Cumulatively, these results indicate that Lkh1 is one of the negative regulators acting upstream of Prk1, regulating non-sexual flocculation in fission yeast.