Protein Kinase A Regulates Sexual Development and Gluconeogenesis through Phosphorylation of the Zn Finger Transcriptional Activator Rst2p in Fission Yeast

Abstract

Protein kinase A (PKAi a cyclic AMP-dependent protein kinase) negatively regulates sexual development and gluconeogenesis in fission yeast by suppressing the transcription of ste11 required for the former and the transcription of fbp1 required for the latter. Here we show that Rst2p, a zinc finger protein that can bind to the upstream region of ste11 and fbp1 via the STREP motif, mediates the activity of PKA to transcription of these genes. A simple reporter system confirmed that PKA could cause its negative effect on transcription through the combination of Rst2p and STREP. Rst2p was phosphorylated by PKA in vitro at two consensus sequences on it. Substitution of the target threonine residues by alanine made the protein active even in the presence of high PKA activity. Rst2p underwent hyperphosphorylation in the medium lacking glucose, and PKA inhibited this hyperphosphorylation. Rst2p was mainly cytoplasmic under high PKA activity but was concentrated in the nucleus when this activity was lowered, suggesting that PKA might regulate ste11 and fbp1 negatively by excluding Rst2p from the nucleus. However, the shift of Rst2p localization was not perfect under physiological conditions, leaving the possibility that PKA inhibits Rst2p function in another way as well. Although the PKA-Rst2p-STREP pathway is apparently central to the regulation of ste11 and fbp1 transcription in accordance with nutritional conditions, some additional paths are likely to connect nitrogen to repression of ste11 and glucose to repression of fbp1. These paths may ensure the specificity between the type of nutrients in shortage and the type of genes to be expressed.

Important Characteristics of Sequence-Specific Recombination Hotspots in Schizosaccharomyces pombe

“…The Rst2 protein is required for full expression of the ste11 and fbp1 genes involved in sexual development and gluconeogenesis, respectively (Kunitomo et al 2000;Higuchi et al 2002). As Ste11 is a crucial transcription factor responsible for regulating the expression of many genes involved in mating and meiosis, rst2 mutants show similar meiotic defects (Kunitomo et al 2000).…”

Antagonistic Controls of Chromatin and mRNA Start Site Selection by Tup Family Corepressors and the CCAAT-Binding Factor

“…fbp1 ϩ expression is strictly repressed by Tup11/12 and activated by the transcriptional activators Atf1, Rst2, and Php5 (23)(24)(25)(26). Atf1, a bZIP protein, is regulated through phosphorylation by the mitogen-activated protein kinase pathway (27)(28)(29), while Rst2, a C 2 H 2 Zn finger-type protein, is under the regulation of the protein kinase A pathway (23,30). Php5, a component of the S. pombe CCAATbinding factor (CBF; also known as NF-Y) that possesses a histone hold domain, forms a complex with Php2/Php3 and contributes to cyc1 ϩ transcription (31,32).…”

Ustilago maydis phosphodiesterases play a role in the dimorphic switch and in pathogenicity

“…In M. oryzae, mutants deleted in both PDEs, PdeH and PdeL, along with higher cAMP levels (~10-fold) in comparison to wild-type, show reduced conidiation and are completely defective in virulence (Ramanujam & Naqvi, 2010). In Schizosaccharomyces pombe, sporulation and mating are regulated via the cAMP-dependent pathway (Higuchi et al, 2002). Also, in U. maydis, deletion mutants in the regulatory subunit of PKA, ubc1, are reduced in pathogenicity and do not produce galls (Gold et al, 1997).…”