THE RNA-POLYMERASE-I TRANSCRIPTION FACTOR UBF IS A SEQUENCE-TOLERANT HMG-BOX PROTEIN THAT CAN RECOGNIZE STRUCTURED NUCLEIC-ACIDS
THE RNA-POLYMERASE-I TRANSCRIPTION FACTOR UBF IS A SEQUENCE-TOLERANT HMG-BOX PROTEIN THAT CAN RECOGNIZE STRUCTURED NUCLEIC-ACIDS
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DOI：
10.1093/nar/22.13.2651
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发表时间：
1994-07-11
影响因子：
14.9
通讯作者：
PIKAARD, CS
中科院分区：
文献类型：
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作者：
COPENHAVER, GP;PUTNAM, CD;PIKAARD, CS
上游结合因子（UBF）对于核糖体RNA转录的激活是重要的，并且属于含有核酸结合结构域（称为HMG盒）的蛋白质家族，其与高迁移率族（HMG）染色体蛋白相似。该家族中的蛋白质可以是序列特异性或高度序列耐受性结合蛋白。我们表明，非洲爪蟾UBF可以被归类为序列耐受类。使用增强子DNA探针的甲基化干扰试验未能揭示UBF结合所需的任何关键核苷酸。通过UBF在具有随机序列的增强子寡核苷酸群体中选择最佳结合位点也未能揭示任何共有序列。小沟特异性药物色霉素A（3）、偏端霉素A和放线菌素D与UBF竞争增强子结合，表明UBF与其他HMG盒蛋白一样，可能与小沟相互作用。UBF还与其他HMG盒蛋白共享结合合成十字形DNA的能力。然而，UBF似乎不同于其他HMG盒蛋白，因为它可以结合RNA（tRNA）和DNA。UBF -核酸相互作用的序列耐受性质可以适应核糖体RNA基因序列的快速进化。
Upstream Binding Factor (UBF) is important for activation of ribosomal RNA transcription and belongs to a family of proteins containing nucleic acid binding domains, termed HMG-boxes, with similarity to High Mobility Group (HMG) chromosomal proteins. Proteins in this family can be sequence-specific or highly sequence-tolerant binding proteins. We show that Xenopus UBF can be classified among the sequence-tolerant class. Methylation interference assays using enhancer DNA probes failed to reveal any critical nucleotides required for UBF binding. Selection by UBF of optimal binding sites among a population of enhancer oligonucleotides with randomized sequences also failed to reveal any consensus sequence. The minor groove specific drugs chromomycin A(3), distamycin A and actinomycin D competed against UBF for enhancer binding, suggesting that UBF, like other HMG-box proteins, probably interacts with the minor groove. UBF also shares with other HMG box proteins the ability to bind synthetic cruciform DNA. However, UBF appears different from other HMG-box proteins in that it can bind both RNA (tRNA) and DNA. The sequence-tolerant nature of UBF - nucleic acid interactions may accommodate the rapid evolution of ribosomal RNA gene sequences.