Sequence specific binding protein of single-stranded and unimolecular quadruplex telomeric DNA from rat hepatocytes
Sequence specific binding protein of single-stranded and unimolecular quadruplex telomeric DNA from rat hepatocytes
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DOI：
10.1074/jbc.272.25.15881
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发表时间：
1997-06-20
影响因子：
4.8
通讯作者：
Fry, M
中科院分区：
文献类型：
--
作者：
Erlitzki, R;Fry, M
描述了大鼠肝核蛋白，单分子四链体端粒结合蛋白 25 (uqTBP25)，其紧密且特异性地结合脊椎动物端粒 DNA 序列 5'-d(TTAGGG)(n)-3' 的单链和单分子四链体形式。通过硫酸铵沉淀、与其他 DNA 结合蛋白的色谱分离和三步柱色谱纯化近均质的 uqTBP25， SDS-聚丙烯酰胺凝胶电泳和 Superdex(C) 200 凝胶过滤公开了 uqTBP25 亚基和天然 M-r 值分别为 25.4 +/- 0.5 和 25.0 kDa，uqTBP25 胰蛋白酶肽的序列与异质核核糖核蛋白 A1、异质核核糖核蛋白 A2/B1 和异质核核糖核蛋白 A2/B1 密切同源，但不相同。单链 DNA 结合蛋白 UP1 和 HDP-1、uqTBP25 与单链或单分子四链体 5'-d(TTAGGG)(4)-3' 的复合物分别具有 2.2 或 13.4 nM 的解离常数 K-d。相对于 d(TAAGGG)(4)，与 5'-r(UUAGGG)(4)-3'、平端双链体端粒 DNA 或四链体端粒 DNA 形成的复合物的 K-d 值高出 >10 至 >250 倍，d(TTAGGG) 重复内的单碱基改变使与 uqTBP25 形成的复合物的 K-d 增加了 9-215 倍，与 uqTBP25 相关保护 d(TTAGGG)(4) 免受核酸酶消化，表明该蛋白质在端粒 DNA 交易中具有潜在作用。
A rat liver nuclear protein, unimolecular quadruplex telomere binding protein 25, (uqTBP25) is described that binds tightly and specifically single stranded and unimolecular tetraplex forms of the vertebrate telomeric DNA sequence 5'-d(TTAGGG)(n)-3', A near homogeneous uqTBP25 was purified by ammonium sulfate precipitation, chromatographic separation from other DNA binding proteins, and three steps of column chromatography, SDS-polyacrylamide gel electrophoresis and Superdex(C) 200 gel filtration disclosed for uqTBP25 subunit and native M-r values of 25.4 +/- 0.5 and 25.0 kDa, respectively, Sequences of uqTBP25 tryptic peptides were closely homologous, but not identical, to heterogeneous nuclear ribonucleoprotein A1, heterogeneous nuclear ribonucleoprotein A2/B1, and single-stranded DNA-binding proteins UP1 and HDP-1, Complexes of uqTBP25 with single-stranded or unimolecular quadruplex 5'-d(TTAGGG)(4)-3', respectively, had dissociation constants, K-d, of 2.2 or 13.4 nM. Relative to d(TAAGGG)(4), complexes with 5'-r(UUAGGG)(4)-3', blunt ended duplex telomeric DNA, or quadruplex telomeric DNA had >10 to >250-fold higher K-d values, Single base alterations within the d(TTAGGG) repeat increased the K-d of complexes with uqTBP25 by 9-215-fold, Association with uqTBP25 protected d(TTAGGG)(4) against nuclease digestion, suggesting a potential role for the protein in telomeric DNA transactions.