Cheung E, Mayr P, Coda-Zabetta F, Woodman P G, Boam D S
School of Biological Sciences, University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT, U.K.
Biochem J. 1999 Nov 15;344 Pt 1(Pt 1):145-52.
The ubiquitous transcription factor upstream stimulatory factor (USF) 1 is a member of the bzHLH (leucine zipper-basic-helix-loop-helix) family, which is structurally related to the Myc family of proteins. It plays a role in the regulation of many genes, including the cyclin B1 gene, which is active during the G2/M and M phases of the cell cycle and may also play a role in the regulation of cellular proliferation. We show that the affinity of recombinant USF-1 for DNA is greatly increased by treatment with active cyclin A2-p34(cdc2) or cyclin B1-p34(cdc2) complexes and that its interaction with DNA is dependent on p34(cdc2)-mediated phosphorylation. We have localized the phosphorylation site(s) to a region that lies outside the minimal DNA-binding domain but overlaps with the previously identified USF-specific region. Deletion studies of USF-1 suggest that amino acids 143-197 regulate DNA-binding activity in a phosphorylation-dependent manner.
普遍存在的转录因子上游刺激因子（USF）1是bzHLH（亮氨酸拉链-碱性螺旋-环-螺旋）家族的成员，在结构上与Myc蛋白家族相关。它在许多基因的调控中发挥作用，包括细胞周期蛋白B1基因，该基因在细胞周期的G2/M期和M期活跃，也可能在细胞增殖调控中发挥作用。我们发现，用活性细胞周期蛋白A2-p34（cdc2）或细胞周期蛋白B1-p34（cdc2）复合物处理后，重组USF-1与DNA的亲和力大大增加，并且其与DNA的相互作用依赖于p34（cdc2）介导的磷酸化。我们已将磷酸化位点定位到一个位于最小DNA结合域外但与先前鉴定的USF特异性区域重叠的区域。USF-1的缺失研究表明，氨基酸143-197以磷酸化依赖的方式调节DNA结合活性。
