The Snf1 protein kinase and its activating subunit, Snf4, interact with distinct domains of the Sip1/Sip2/Ga183 component in the kinase complex
The Snf1 protein kinase and its activating subunit, Snf4, interact with distinct domains of the Sip1/Sip2/Ga183 component in the kinase complex
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DOI：
10.1128/mcb.17.4.2099
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发表时间：
1997-04-01
影响因子：
5.3
通讯作者：
Carlson, M
中科院分区：
文献类型：
--
作者：
Jiang, R;Carlson, M
Snf1 蛋白激酶在酿酒酵母对葡萄糖饥饿的反应中发挥着核心作用。之前，我们发现高水平的葡萄糖会抑制 Snf1 及其激活亚基 Snf4 之间的双杂交相互作用。这些发现，加上 Snf1 和 Snf4 在葡萄糖中生长的细胞中仍然相关的生化证据，表明另一种蛋白质（或多种蛋白质）将 Snf1 和 Snf4 锚定成复合物。在这里，我们研究了由 Sip1、Sip2 和 Ga183 组成的蛋白质家族服务于此目的的可能性。我们首先表明，在 sip1 Delta sip2 Delta ga183 Delta 三重突变体中，与 Snf1 复合的细胞 Snf4 蛋白的比例减少。然后我们提供证据表明 Sipl、Sip2 和 Ga183 各自通过不同的结构域独立地与 Snf1 和 Snf4 相互作用。保守的内部区域与 Snf1 调节域结合，保守的 C 端 ASC 域与 Snf4 结合。通过使用双杂交系统绘制相互作用图谱，并通过体外结合研究得到证实。这些发现表明 Sip1/Sip2/Ga183 家族将 Snf1 和 Snf4 锚定成复合物。最后，酵母 Sip2 蛋白与植物 Snf1 同源物的相互作用表明该功能在植物中是保守的。
The Snf1 protein kinase plays a central role in the response to glucose starvation in the yeast Saccharomyces cerevisiae. Previously, we showed that two-hybrid interaction between Snf1 and its activating subunit, Snf4, is inhibited by high levels of glucose. These findings, together with biochemical evidence that Snf1 and Snf4 remain associated in cells grown in glucose, suggested that another protein (or proteins) anchors Snf1 and Snf4 into a complex. Here, we examine the possibility that a family of proteins, comprising Sip1, Sip2, and Ga183, serves this purpose. We first show that the fraction of cellular Snf4 protein that is complexed with Snf1 is reduced in a sip1 Delta sip2 Delta ga183 Delta triple mutant. We then present evidence that Sipl, Sip2, and Ga183 each interact independently with both Snf1 and Snf4 via distinct domains. A conserved internal region binds to the Snf1 regulatory domain, and the conserved C-terminal ASC domain binds to Snf4. Interactions were mapped by using the two-hybrid system and were confirmed by in vitro binding studies. These findings indicate that the Sip1/Sip2/Ga183 family anchors Snf1 and Snf4 into a complex. Finally, the interaction of the yeast Sip2 protein with a plant Snf1 homolog suggests that this function is conserved in plants.