CK2 phosphorylates SSRP1 and inhibits its DNA-binding activity
CK2 phosphorylates SSRP1 and inhibits its DNA-binding activity
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DOI：
10.1074/jbc.m413944200
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发表时间：
2005-03-25
影响因子：
4.8
通讯作者：
Lu, H
中科院分区：
文献类型：
--
作者：
Li, YP;Keller, DM;Lu, H
我们以前已经表明，CK 2与人类高迁移率族蛋白SSRP 1，这种关联增加响应紫外线照射。CK 2也在体外磷酸化SSRP 1。在这里，我们通过研究CK 2通过磷酸化对SSRP 1功能的调节来扩展这项工作。CK 2对SSRP 1的磷酸化可抑制SSRP 1与FACT（facilitating chromatin-mediated transcription）复合物的非特异性DNA结合活性。使用丝氨酸/苏氨酸扫描Auto-spot肽阵列，结合以合成肽为底物的基于过滤的激酶测定，我们在体外鉴定了丝氨酸510、657和688作为CK 2的磷酸化靶点。三个丝氨酸的突变显示，丝氨酸510是更重要的SSRP 1 DNA结合活性的调节。此外，我们发现SSRP 1在细胞中对UV（而不是γ）照射的反应是磷酸化的。这些结果表明，CK 2调节SSRP 1的DNA结合能力，这种调节可能是响应特定的细胞应激。
We have previously shown that CK2 associates with the human high-mobility group protein SSRP1 and that this association increases in response to UV irradiation. CK2 also phosphorylates SSRP1 in vitro. Here we extend this work by investigating CK2 regulation of SSRP1 function through phosphorylation. Phosphorylation of SSRP1 by CK2 inhibited the nonspecific DNA-binding activity of SSRP1 and FACT (facilitating chromatin-mediated transcription) complex in vitro. Using a serine/threonine-scanning Auto-spot peptide array coupled with a filter-based kinase assay with synthetic peptides as substrates, we identified serines 510, 657, and 688 as phosphorylation targets of CK2 in vitro. Mutagenesis of the three serines revealed that serine 510 was more important for the regulation of SSRP1 DNA-binding activity. Furthermore, we found that SSRP1 was phosphorylated in cells in response to UV (but not gamma) irradiation. These results suggest that CK2 regulates the DNA-binding ability of SSRP1 and that this regulation may be responsive to specific cell stresses.