Mug27 is a meiosis-specific protein kinase that functions in fission yeast meiosis II and sporulation

Several meiosis-specific proteins of Schizosaccharomyces pombe play essential roles in meiotic progression. We report here that a novel meiosis-specific protein kinase, Mug27 (also known as Ppk35), is required for proper spore formation. This kinase is expressed by the mug27⁺ gene, which is abruptly transcribed after horsetail movement. This transcription is maintained until the second meiotic division. Green fluorescent protein (GFP)-tagged Mug27 appears at the start of prometaphase I, localizes to the spindle pole body (SPB) and then translocates to the forespore membrane (FSM) at late anaphase II. In the mug27 strain, smaller spores are produced compared with those of the mug27⁺ strain. Moreover, spore viability was reduced by half or more compared with that of the mug27⁺ strain. The protein-kinase activity of Mug27 appears to be important for its function: the putative kinase-dead Mug27 mutant had similar phenotypes to mug27. Our results here indicate that the Mug27 kinase localizes at the SPB and regulates FSM formation and sporulation.