The yeast MCK1 gene encodes a protein kinase homolog that activates early meiotic gene expression.

Abstract

We have identified a yeast gene, MCK1, that encodes a positive regulator of meiosis and spore formation. Sequence analysis revealed that MCK1 encodes a protein kinase homolog identical to YPK1, a phosphotyrosyl protein with demonstrated protein kinase activity. Increased MCK1 gene dosage accelerates the sporulation program; mckl mutations cause delayed and decreased levels of sporulation. MCK1 is required during sporulation for maximal transcript accumulation from IME1, which encodes a meiotic activator. MCK1 is required in vegetative cells for basal IME1 expression, as evidenced by functional assays of an imel-HIS3 fusion gene. MCK1 is also required for efficient ascus maturation. Although expression of IME1 from the GALl promoter restored high-level sporulation to mckl mutants, it did not correct the ascus-maturation defect. This observation indicates that MCK1 is required, independently, for both the activation of IME1 and subsequent ascus maturation. Expression of an mckl-lacZ fusion gene was not regulated by the signals that govern meiosis. This observation is consistent with evidence that MCK1 plays a role in governing centromere function during vegetative growth as well as sporulation.

Mutation of the SPS1-encoded protein kinase of Saccharomyces cerevisiae leads to defects in transcription and morphology during spore formation.

“…Entry into meiosis is regulated in part by a decrease in the activity of cAMP-dependent protein kinase in response to nutrient limitation (for re view, see Broach 1991). The expression of IMEl, a key regulatory gene required for almost all meiotic gene ex pression (for review, see Mitchell 1994), is stimulated by MCKl, which encodes a dual specificity kinase (Dailey et al 1990;Neigebom and Mitchell 1991). This kinase also plays a role in ascus maturation (Neigebom and Mitchell 1991) and centromere function (Shero and Hieter 1991).…”

“…The expression of IMEl, a key regulatory gene required for almost all meiotic gene ex pression (for review, see Mitchell 1994), is stimulated by MCKl, which encodes a dual specificity kinase (Dailey et al 1990;Neigebom and Mitchell 1991). This kinase also plays a role in ascus maturation (Neigebom and Mitchell 1991) and centromere function (Shero and Hieter 1991). The RIMll-encoded kinase is required for Imel to activate expression of IME2 (Mitchell and Bowdish 1992;Smith et al 1993;Mitchell 1994).…”

Nutritional Regulation of Meiosis-specific Gene Expression in Saccharomyces cerevisiae

“…5) We report here studies on the remaining two plasmids (pSP2 and pSP3). Restriction mapping analysis (described below) of the yeast inserts cloned on pSP2 and pSP3 found no similarity to IMEl,3) IME2, 4,5) or MCKl,14) and therefore represents new loci The a/a diploid cells (AMI205-9B x YIY344) were transformed with each plasmid (e, pSPI; ... , pSP2; ., pSP3; and 0, pYIl). The plasmids pSPl, pSP2, and pSP3…”

Yeast Glycogen Synthase Kinase-3 Activates Msn2p-dependent Transcription of Stress Responsive Genes

“…Mck1p plays a role in mitotic chromosomal segregation specific to CDEIII function (Shero and Hieter, 1991), acts in the transcription of IME1 at the beginning of meiosis (Neigeborn and Mitchell, 1991), and is important for inducing the cell cycle delay in response to Ca 2ϩ (Mizunuma et al, 2001). Mds1p/Rim11p plays a role in expression of meiotic genes by phosphorylating Ime1p and Ume6p (Bowdish et al, 1994;Xiao and Mitchell, 2000).…”