NRS1, a nitrogen source-regulated microprotein, confers an alternative mechanism of G1/S transcriptional activation in budding yeast
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ABSTRACT: Commitment to cell division at the end of G1 phase, termed Start in the budding yeast Saccharomyces cerevisiae, is strongly influenced by nutrient availability. To identify newdominant activators of Start that might operate under different nutrient conditions, we screened a genome-wide ORF overexpression library for genes that bypass a Start arrest caused by absence of the G1 cyclin Cln3 and the transcriptional activator Bck2. We recovered a hypothetical gene YLR053c, renamed NRS1 for Nitrogen-responsive Start Regulator 1, which encodes a poorly characterized 108 amino acid microprotein. Endogenous NRS1 was nuclear-localized, restricted to poor nitrogen conditions, induced upon mTORC1 inhibition, and cell cycle-regulated with a peak at Start. NRS1 interacted genetically with SWI4 and SWI6, which encode the master G1/S transcription factor complex SBF. Correspondingly, NRS1 physically interacted with Swi4 and Swi6 and was localized to G1/S promoter DNA. NRS1 exhibited inherent transactivation activity and fusion of NRS1 to the SBF inhibitor Whi5 was sufficient to suppress other Start defects. NRS1 appears to be a recently evolved microprotein that rewires the G1/S transcriptional machinery under poor nutrient conditions.
INSTRUMENT(S): Q Exactive HF
ORGANISM(S): Saccharomyces Cerevisiae (baker's Yeast)
TISSUE(S): Cell Culture
SUBMITTER: Eric Bonneil
LAB HEAD: Mike Tyers
PROVIDER: PXD018681 | Pride | 2021-08-25
REPOSITORIES: Pride
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