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