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Mol. Cell. Biol., 10 1995, 5279-5287, Vol 15, No. 10
RA Sia and AP Mitchell
Ime2p is a protein kinase that is expressed only during meiosis in
Saccharomyces cerevisiae. Ime2p stimulates early, middle, and late meiotic
gene expression and down-regulates expression of IME1, which specifies an
activator of early meiotic genes that acts independently of Ime2p. We have
identified a new gene, IDS2 (for IME2-dependent signaling), which has a
functional relationship to Ime2p. An ids2 null mutation delays
down-regulation of IME1 and expression of middle and late meiotic genes. In
an ime1 null mutant that express IME2 from the GAL1 promoter (ime1 delta
PGAL1-IME2 mutant), early meiotic gene expression depends only upon Ime2p.
In such strains, Ids2p is dispensable for expression of the early genes
HOP1 and SPO13 but is essential for expression of the middle and late genes
SPS1, SPS2, and SPS100. Ids2p is also essential for the autoregulatory
pathway through which Ime2p activates its own expression via the IME2
upstream activation sequences (UAS). An PGAL1-IME2 derivative that produces
a truncated Ime2p (lacking its C-terminal 174 residues) permits IME2 UAS
activation in the absence of Ids2p. This observation suggests that Ids2p
acts upstream of Ime2p or that Ids2p and Ime2p act in independent,
convergent pathways to stimulate IME2 UAS activity. Accumulation of
epitope-tagged Ids2p derivatives is greatest in growing cells and declines
during meiosis. We propose that Ids2p acts indirectly to modify Ime2p
activity, thus permitting Ime2p to carry out later meiotic functions.
Copyright © 1995, American Society for Microbiology
Stimulation of later functions of the yeast meiotic protein kinase Ime2p by the IDS2 gene product
Department of Microbiology, Columbia University, New York, New York 10032, USA.
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