Interaction between the transmembrane domains of Sho1 and Opy2 enhances the signaling efficiency of the Hog1 MAP kinase cascade in Saccharomyces cerevisiae
Interaction between the transmembrane domains of Sho1 and Opy2 enhances the signaling efficiency of the Hog1 MAP kinase cascade in Saccharomyces cerevisiae
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DOI：
10.1371/journal.pone.0211380
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发表时间：
2019-01-25
期刊：
影响因子：
3.7
通讯作者：
Tatebayashi, Kazuo
中科院分区：
文献类型：
--
作者：
Takayama, Tomomi;Yamamoto, Katsuyoshi;Tatebayashi, Kazuo
为了科普增加的细胞外渗透压，芽殖酵母酿酒酵母激活Hog 1丝裂原活化蛋白激酶（MAPK），其控制各种适应性反应。Hog 1通过高渗透压甘油（HOG）途径激活，该途径由核心MAPK级联和两个独立的上游分支（SHO 1和SLN 1分支）组成，所述上游分支含有不同的甘油敏感机制。在SHO 1分支中，Sho 1的同源寡聚体（四跨膜（TM）共刺激传感器）通过其TM结构域与跨膜共刺激传感器Hkr 1和Msb 2以及膜锚蛋白Opy 2相互作用，并激活Ste 20-Ste 11-Pbs 2-Hog 1激酶级联。在这项研究中，我们分离和分析了多动突变体的Sho 1和Opy 2，港口突变在其TM域。几个过度活跃的突变增强了Sho 1和Opy 2之间的相互作用，表明TM介导的Sho 1和Opy 2之间的相互作用对促进有效信号传导的重要性。Sho 1和Opy 2的TM结构域之间的相互作用将使它们各自的细胞质结合配偶体Pbs 2和Ste 11非常接近。事实上，对突变体的遗传分析表明，Sho 1-Opy 2相互作用增强了Ste 11对Pb 2的激活，但没有增强Pb 2对Hog 1的激活。一些高活性突变体在Sho 1 TM 4或Opy 2 TM的细胞外末端具有突变，并定义了Sho 1-Opy 2结合位点1（BS 1）。化学交联和突变分析表明，Sho 1 TM 1和Opy 2 TM的胞质末端也相互作用，定义了Sho 1-Opy 2结合位点2（BS 2）。一个几何的考虑约束，一个Opy 2分子必须与两个相邻的Sho 1分子在Sho 1寡聚体。这些结果提出了一种可能性，即Sho 1-Opy 2复合物的构象的改变可能有助于Hog 1 MAPK级联的渗透激活。
To cope with increased extracellular osmolarity, the budding yeast Saccharomyces cerevisiae activates the Hog1 mitogen-activated protein kinase (MAPK), which controls a variety of adaptive responses. Hog1 is activated through the high-osmolarity glycerol (HOG) pathway, which consists of a core MAPK cascade and two independent upstream branches (SHO1 and SLN1 branches) containing distinct osmosensing machineries. In the SHO1 branch, a homo-oligomer of Sho1, the four-transmembrane (TM) osmosensor, interacts with the transmembrane co-osmosensors, Hkr1 and Msb2, and the membrane anchor protein Opy2, through their TM domains, and activates the Ste20-Ste11-Pbs2-Hog1 kinase cascade. In this study, we isolated and analyzed hyperactive mutants of Sho1 and Opy2 that harbor mutations within their TM domains. Several hyperactive mutations enhanced the interaction between Sho1 and Opy2, indicating the importance of the TM-mediated interaction between Sho1 and Opy2 for facilitating effective signaling. The interaction between the TM domains of Sho1 and Opy2 will place their respective cytoplasmic binding partners Pbs2 and Ste11 in close proximity. Indeed, genetic analyses of the mutants showed that the Sho1-Opy2 interaction enhances the activation of Pbs2 by Ste11, but not Hog1 by Pbs2. Some of the hyperactive mutants had mutations at the extracellular ends of either Sho1 TM4 or Opy2 TM, and defined the Sho1-Opy2 binding site 1 (BS1). Chemical crosslinking and mutational analyses revealed that the cytoplasmic ends of Sho1 TM1 and Opy2 TM also interact with each other, defining the Sho1-Opy2 binding site 2 (BS2). A geometric consideration constrains that one Opy2 molecule must interact with two adjacent Sho1 molecules in Sho1 oligomer. These results raise a possibility that an alteration of the conformation of the Sho1-Opy2 complex might contributes to the osmotic activation of the Hog1 MAPK cascade.