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

Abstract

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.

The Dual-Specificity LAMMER Kinase Affects Stress-Response and Morphological Plasticity in Fungi

“…Consistent with the prk1 + -deletion and -overexpression experiments, the transcriptional level of prk1 + is also significantly decreased in the Splkh1Δ mutant, indicating that Prk1 functions at the downstream pathway of SpLkh1-mediated non-sexual flocculation. In addition, non-sexual flocculation of the prk1 + -deletion mutant cells is galactose-specific and divalent-cation-dependent (Park et al, 2018), which is similar to the case with the Splkh1Δ mutant (Kim et al, 2001). The flocculation in submerged culture and filamentous growth on agar surface shown by the Splkh1Δ mutant appear to result from changes of cell wall proteins in S. pombe ; Polyacrylamide gel electrophoresis and subsequent identification of differentially expressed extracellular proteins from wild-type and Splkh1Δ mutant cells by tandem mass spectrometry reveal the upregulation of the glycolipid-anchored surface precursor β-glucosidase, the cell surface 1,3-β-glucosidase, and exo-1,3 β-glucanase in the Splkh1Δ mutant (Cho et al, 2010).…”

“…Non-sexual flocculation in S. pombe is induced by the deletion of factors, which negatively regulates the expression of cell-surface flocculins, such as Prk1 (Watson and Davey, 1998), transcriptional repressors Tup11 and 12 (Kang et al, 2010), and the ribosomal protein Rlp32 (Li et al, 2013; Liu et al, 2015), and by the overexpression of some adhesins (Matsuzawa et al, 2011). The flocculating activity of the Splkh1Δ mutant (Kim et al, 2001) is increased by the additional deletion of the prk1 + gene, but is nullified by the overexpression of Prk1 (Park et al, 2018). Consistent with the prk1 + -deletion and -overexpression experiments, the transcriptional level of prk1 + is also significantly decreased in the Splkh1Δ mutant, indicating that Prk1 functions at the downstream pathway of SpLkh1-mediated non-sexual flocculation.…”

LAMMER Kinase Modulates Cell Cycle by Phosphorylating the MBF Repressor, Yox1, in Schizosaccharomyces pombe

“…LAMMER kinases in various yeasts and filamentous fungi also share similar functions [ 2 ]. In the fission yeast Schizosaccharomyces pombe ( S. pombe ), Lkh1 plays roles in growth, flocculation, oxidative stress response, cell cycle, and sexual differentiation [ 3–6 ]. In the budding yeast Saccharomyces cerevisiae ( S. cerevisiae ), Kns1 is involved in adhesive filamentous growth, temperature sensing, and tRNA biogenesis [ 7–9 ].…”