Snf1 kinase and the repressors Nrg1 and Nrg2 regulate FLO11
expression, invasive growth, and pseudohyphal development.
Sergei Kuchin, Valmik K. Vyas, Marian Carlson
Institute of
Cancer Research, Columbia University, 701 West 168th St., New York, NY
10032, USA
The Snf1 protein kinase has important roles in cellular
responses to glucose limitation, including developmental responses such
as haploid invasive growth (Cullen and Sprague, PNAS 97:13619, 2000). We
present evidence that the Snf1 kinase positively regulates transcription
of FLO11, which encodes a cell-surface glycoprotein required for
invasive growth. Nrg1 and Nrg2, two repressor proteins that interact
with Snf1, function as repressors of FLO11 and negatively
regulate invasive growth. We also examined the role of the Snf1 kinase
and the Nrg proteins in two other Flo11-dependent processes. Mutations
in the corresponding genes affected adherence to plastic, suggesting a
role in biofilm formation. They also affected diploid pseudohyphal
differentiation, thereby unexpectedly implicating Snf1 in a response to
nitrogen limitation. Deletion of NRG1 and NRG2 suppressed
the defects of a snf1 mutant in all of these processes. We
propose that the Snf1 kinase positively regulates diverse Flo11-dependent developmental events, at least in part, by antagonizing Nrg-mediated repression of FLO11.
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