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

Abstract

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 mug27Δ 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 mug27Δ. Our results here indicate that the Mug27 kinase localizes at the SPB and regulates FSM formation and sporulation.

Dma1-dependent degradation of Septation Initiation Network proteins during meiosis inSchizosaccharomyces pombe

“…Heat-sensitive and null mutants have implicated the SIN and its regulators in spore formation (Krapp et al, 2006;Ohtaka et al, 2008;Pérez-Hidalgo et al, 2008;Yan et al, 2008). We extended this analysis to other components of the SIN.…”

“…Loss of SIN signalling produces multinucleate cells, whereas constant activation of the SIN results in multiseptated cells (reviewed by Goyal et al, 2011;. The SIN is also essential during meiosis (Krapp et al, 2006;Ohtaka et al, 2008;Pérez-Hidalgo et al, 2008;Yan et al, 2008) -SIN mutants complete both meiotic divisions, but fail to form spores. SIN signalling is modulated by the nucleotide status of the GTPase Spg1p (Schmidt et al, 1997;Sohrmann et al, 1998), which is regulated by the balance of spontaneous nucleotide exchange, and a GTPase-activating protein (GAP), Cdc16p Minet et al, 1979), with which Spg1p interacts through a scaffold, Byr4p (Furge et al, 1999;Furge et al, 1998;Song et al, 1996).…”

“…During meiosis II, Cdc16p disappears from the SPBs, to be replaced by Cdc7p and Sid1p-Cdc14p. A Sid2p-related protein kinase called Mug27 (also known as Ppk35 or Slk1) is expressed specifically during meiosis (Ohtaka et al, 2008;Pérez-Hidalgo et al, 2008;Yan et al, 2008). Mug27p localises to the SPB during nuclear division and associates with the FSM during spore formation before being degraded at the end of meiosis II.…”

“…Mug27p localises to the SPB during nuclear division and associates with the FSM during spore formation before being degraded at the end of meiosis II. It does not require the SIN scaffold proteins for association with the SPB (Ohtaka et al, 2008). Increased expression of the syntaxin Psy1p rescues the sporulation defect of mug27-D sid2-250 (Yan et al, 2008), suggesting that Mug27p and Sid2p cooperate to promote the recruitment of components of the secretory apparatus to allow FSM expansion.…”

“…Increased expression of the syntaxin Psy1p rescues the sporulation defect of mug27-D sid2-250 (Yan et al, 2008), suggesting that Mug27p and Sid2p cooperate to promote the recruitment of components of the secretory apparatus to allow FSM expansion. Previous studies have shown that the association of all the SIN proteins with the SPB during meiosis depends upon the scaffold proteins Sid4p and Cdc11p (Krapp et al, 2006;Ohtaka et al, 2008;Yan et al, 2008). However, the hierarchy of localisation of the other SIN proteins in meiosis has not been investigated in detail.…”