Tor2 directly phosphorylates the AGC kinase Ypk2 to regulate actin polarization
Tor2 directly phosphorylates the AGC kinase Ypk2 to regulate actin polarization
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DOI：
10.1128/mcb.25.16.7239-7248.2005
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发表时间：
2005-08-01
影响因子：
5.3
通讯作者：
Ohsumi, Y
中科院分区：
文献类型：
--
作者：
Kamada, Y;Fujioka, Y;Ohsumi, Y
雷帕霉素（TOR）蛋白激酶的靶点Tor 1和Tor 2在酵母酿酒酵母中形成两种不同的复合物（TOR复合物I和2）。TOR复合物2（TORC 2）含有Tor 2但不含Tor 1，并通过Rho 1/Pkc 1/MAPK细胞完整性级联反应控制肌动蛋白细胞骨架的极性。TORC 2的底物以及TORC 2如何调节细胞完整性途径尚不清楚。筛选tor 2的多拷贝抑制子，我们获得了表达N-末端截短的Ypk 2蛋白激酶的质粒。这种截短似乎部分破坏了Ypk 2中的自抑制结构域，并且该区域中的点突变（Ypk 2（D239 A））赋予全长Ypk 2拯救在TORC 2而不是TORCI功能中受损的细胞生长的能力。YPK 2（D239 A）还抑制tor 2 δ细胞的致死性，表明Ypks在TORC 2信号传导中起重要作用。Ypk 2在体外被Tor 2直接磷酸化，并且Ypk 2活性在Tor 2 Delta细胞中大大降低。相比之下，Ypk 2（D239 A）在体内具有增加的且不依赖于TOR 2的活性。因此，我们认为Ypk蛋白激酶是TORC 2的直接和必要的靶点，将TORC 2与细胞完整性级联反应偶联。
The target of rapamycin (TOR) protein kinases, Tor1 and Tor2, form two distinct complexes (TOR complex I and 2) in the yeast Saccharomyces cerevisiae. TOR complex 2 (TORC2) contains Tor2 but not Tor1 and controls polarity of the actin cytoskeleton via the Rho1/Pkc1/MAPK cell integrity cascade. Substrates of TORC2 and how TORC2 regulates the cell integrity pathway are not well understood. Screening for multicopy suppressors of tor2, we obtained a plasmid expressing an N-terminally truncated Ypk2 protein kinase. This truncation appears to partially disrupt an autoinhibitory domain in Ypk2, and a point mutation in this region (Ypk2(D239A)) conferred upon full-length Ypk2 the ability to rescue growth of cells compromised in TORC2, but not TORCI, function. YPK2(D239A) also suppressed the lethality of tor2 Delta cells, suggesting that Ypks play an essential role in TORC2 signaling. Ypk2 is phosphorylated directly by Tor2 in vitro, and Ypk2 activity is largely reduced in tor2 Delta cells. In contrast, Ypk2(D239A) has increased and TOR2-independent activity in vivo. Thus, we propose that Ypk protein kinases are direct and essential targets of TORC2, coupling TORC2 to the cell integrity cascade.