Norbeck J, Blomberg A
Department of Cell and Molecular Biology, Lundberg Laboratory, Göteborg University, Medicinaregatan 9C, SE-41390 Göteborg, Sweden.
Yeast. 2000 Jan 30;16(2):121-37. doi: 10.1002/(SICI)1097-0061(20000130)16:2<121::AID-YEA511>3.0.CO;2-A.
The influence of cAMP-dependent protein kinase (PKA) on protein expression during exponential growth under osmotic stress was studied by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The responses of isogenic strains (tpk2Deltatpk3Delta) with either constitutively low (tpk1(w1)), regulated (TPK1) or constitutively high (TPK1bcy1Delta) PKA activity were compared. The activity of cAMP-dependent protein kinase (PKA) was shown to be a major determinant of osmotic shock tolerance. Proteins with increased expression during growth under sodium chloride stress could be grouped into three classes with respect to PKA activity, with the glycerol metabolic proteins GPD1, GPP2 and DAK1 standing out as independent of PKA. The other osmotically induced proteins displayed a variable dependence on PKA activity; fully PKA-dependent genes were TPS1 and GCY1, partly PKA-dependent genes were ENO1, TDH1, ALD3 and CTT1. The proteins repressed by osmotic stress also fell into distinct classes of PKA-dependency. Ymr116c was PKA-independent, while Pgi1p, Sam1p, Gdh1p and Vma1p were fully PKA-dependent. Hxk2p, Pdc1p, Ssb1p, Met6p, Atp2p and Hsp60p displayed a partially PKA-dependent repression. The promotors of all induced PKA-dependent genes have STRE sites in their promotors suggestive of a mechanism acting via Msn2/4p. The mechanisms governing the expression of the other classes are unknown. From the protein expression data we conclude that a low PKA activity causes a protein expression resembling that of osmotically stressed cells, and furthermore makes cells tolerant to this type of stress.
通过二维聚丙烯酰胺凝胶电泳（2D-PAGE）研究了环磷酸腺苷依赖性蛋白激酶（PKA）在渗透胁迫下指数生长期间对蛋白质表达的影响。比较了具有组成型低（tpk1(w1)）、调节型（TPK1）或组成型高（TPK1bcy1Delta）PKA活性的同基因菌株（tpk2Deltatpk3Delta）的反应。结果表明，环磷酸腺苷依赖性蛋白激酶（PKA）的活性是渗透休克耐受性的主要决定因素。在氯化钠胁迫下生长期间表达增加的蛋白质，就PKA活性而言可分为三类，甘油代谢蛋白GPD1、GPP2和DAK1不受PKA影响。其他渗透诱导蛋白对PKA活性的依赖性各不相同；完全依赖PKA的基因是TPS1和GCY1，部分依赖PKA的基因是ENO1、TDH1、ALD3和CTT1。受渗透胁迫抑制的蛋白质也分为不同的PKA依赖性类别。Ymr116c不依赖PKA，而Pgi1p、Sam1p、Gdh1p和Vma1p完全依赖PKA。Hxk2p、Pdc1p、Ssb1p、Met6p、Atp2p和Hsp60p表现出部分依赖PKA的抑制作用。所有诱导的依赖PKA的基因的启动子在其启动子中都有STRE位点，提示存在一种通过Msn2/4p起作用的机制。其他类别的表达调控机制尚不清楚。根据蛋白质表达数据，我们得出结论，低PKA活性导致蛋白质表达类似于渗透胁迫细胞的表达，并且还使细胞对这种类型的胁迫具有耐受性。
