Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.
FEBS Lett. 2011 Oct 3;585(19):3026-32. doi: 10.1016/j.febslet.2011.08.023. Epub 2011 Aug 27.
In Saccharomyces cerevisiae PKA plays a major role in regulating cell growth, metabolism, and stress resistance. We report that Sch9 regulates PKA directly and SCH9 deletion enhances PKA activity by showing that: (1) Bcy1 predominately localized in the nucleus in glycerol-grown sch9Δ cells; (2) large part of the catalytic subunits of PKA transferred from the nucleus to the cytoplasm in sch9Δ cells; (3) higher protein stability of Tpk2 resulted in higher protein level of Tpk2 in sch9Δ than in wild type cells. Our investigations suggest that Sch9 regulates phosphorylation of Bcy1. We also observed hyper-phosphorylation of Cdc25 in sch9Δ, in contrast to the tpk2Δ and tpk2Δsch9Δ mutants, suggesting that feedback inhibition of PKA on Cdc25 is through Tpk2.
在酿酒酵母中，PKA 在调节细胞生长、代谢和应激抗性方面发挥着重要作用。我们报告说，Sch9 直接调节 PKA，并且 SCH9 缺失通过以下方式增强 PKA 活性：（1）Bcy1 在甘油生长的 sch9Δ细胞中主要定位于核内；（2）PKA 的大部分催化亚基从核内转移到 sch9Δ细胞的细胞质中；（3）Sch9 调节 Bcy1 的磷酸化。我们还观察到 sch9Δ 中 Cdc25 的过度磷酸化，与 tpk2Δ 和 tpk2Δsch9Δ 突变体相反，表明 PKA 对 Cdc25 的反馈抑制是通过 Tpk2 实现的。
