Budding yeast Rad9 is an ATP-dependent Rad53 activating machine
Budding yeast Rad9 is an ATP-dependent Rad53 activating machine
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DOI：
10.1016/s1097-2765(01)00267-2
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发表时间：
2001-07-01
期刊：
影响因子：
16
通讯作者：
Lowndes, NF
中科院分区：
文献类型：
--
作者：
Gilbert, CS;Green, CM;Lowndes, NF
我们发现芽殖酵母Rad 9在两个不同的，大的，可溶性复合物的细胞提取物。在未受损细胞中发现的较大（大于或等于850 kDa）复合物含有低磷酸化的Rad 9，而在DNA损伤后形成的较小（560 kDa）复合物含有高磷酸化的Rad 9和Rad 53。这种较小的Rad 9复合物能够催化磷酸化和活性Rad 53激酶的释放，这是一个需要Rad 53激酶活性的过程。然而，一旦560 kDa复合物形成，Mec 1和Tel 1就不再需要。我们提出了一个模型，其中Mec 1/Tel 1依赖的过度磷酸化的Rad 9的结果在形成较小的Rad 9复合物和招聘的Rad 53。然后，该复合物通过充当使Rad 53分子紧密接近的支架来催化Rad 53的活化，促进Rad 53的反式自磷酸化和随后的活化Rad 53的释放。
We find budding yeast Rad9 in two distinct, large, and soluble complexes in cell extracts. The larger (greater than or equal to 850 kDa) complex, found in nondamaged cells, contains hypophosphorylated Rad9, whereas the smaller (560 kDa) complex, which forms after DNA damage, contains hyperphosphorylated Rad9 and Rad53. This smaller Rad9 complex is capable of catalyzing phosphorylation and release of active Rad53 kinase, a process requiring the kinase activity of Rad53. However, Mec1 and Tel1 are no longer required once the 560 kDa complex has been formed. We propose a model whereby Mec1/Tel1-dependent hyperphosphorylation of Rad9 results in formation of the smaller Rad9 complex and recruitment of Rad53. This complex then catalyzes activation of Rad53 by acting as a scaffold that brings Rad53 molecules into close proximity, facilitating Rad53 in trans autophosphorylation and subsequent release of activated Rad53.