MULTIPLE DOMAINS OF THE RNA POLYMERASE-I ACTIVATOR HUBF INTERACT WITH THE TATA-BINDING PROTEIN COMPLEX HSL1 TO MEDIATE TRANSCRIPTION
MULTIPLE DOMAINS OF THE RNA POLYMERASE-I ACTIVATOR HUBF INTERACT WITH THE TATA-BINDING PROTEIN COMPLEX HSL1 TO MEDIATE TRANSCRIPTION
复制标题
DOI：
10.1101/gad.6.10.1950
复制
发表时间：
1992-10-01
影响因子：
10.5
通讯作者：
TJIAN, R
中科院分区：
文献类型：
--
作者：
JANTZEN, HM;CHOW, AM;TJIAN, R
最近的证据表明，转录起始的所有三个真核RNA聚合酶涉及的TATA结合蛋白（TBP）和多个TBP相关因子（TAF）的复合物。在这里，我们映射的核仁HMG盒蛋白hUBF，它结合到人类rRNA启动子和刺激转录的RNA聚合酶I通过与一个独特的TBP-TAF复合物，hSL 1的合作相互作用的功能域。突变hUBF蛋白和84个氨基酸的合成肽的DNA酶I足迹分析表明，HMG盒1是必要的和足够的DNA序列特异性，而其他HMG盒和氨基末端调节的结合效率。hUBF含有多个活化结构域，包括酸性羧基末端和三个HMG盒。HMG盒3和4和酸性尾显著有助于在hSL 1存在下的扩展足迹模式，提示特异性蛋白质-蛋白质相互作用。此外，非洲爪蟾的xUBF不能与hSL 1形成起始复合物，这可以通过含有人HMG盒4和酸性羧基末端的杂合蛋白来克服。这些结果有力地表明了hUBF的转录激活结构域在介导与TBP-TAF复合物hSL 1的相互作用中的重要作用。
Recent evidence suggests that transcription initiation by all three eukaryotic RNA polymerases involves a complex of the TATA-binding protein (TBP) and multiple TBP-associated factors (TAFs). Here, we map the functional domains of the nucleolar HMG box protein hUBF, which binds to the human rRNA promoter and stimulates transcription by RNA polymerase I through cooperative interactions with a distinct TBP-TAF complex, hSL1. DNase I footprint analysis of mutant hUBF proteins and of a synthetic peptide of 84 amino acids reveals that HMG box 1 is necessary and sufficient for DNA sequence specificity, whereas other HMG boxes and the amino terminus modulate the binding efficiency. hUBF contains multiple activation domains that include the acidic carboxyl terminus and three HMG boxes. HMG boxes 3 and 4 and the acidic tail contribute significantly to an extended footprinting pattern in the presence of hSL1, suggestive of specific protein-protein interactions. Moreover, the inability of xUBF from Xenopus laevis to form an initiation complex with hSL1 can be overcome by hybrid proteins containing human HMG box 4 and the acidic carboxyl terminus. These results strongly suggest an important role of transcription activation domains of hUBF in mediating interactions with the TBP-TAF complex hSL1.