AMINO-ACID CHANGES IN CONSERVED REGIONS OF THE BETA-SUBUNIT OF ESCHERICHIA-COLI RNA-POLYMERASE ALTER TRANSCRIPTION PAUSING AND TERMINATION
AMINO-ACID CHANGES IN CONSERVED REGIONS OF THE BETA-SUBUNIT OF ESCHERICHIA-COLI RNA-POLYMERASE ALTER TRANSCRIPTION PAUSING AND TERMINATION
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DOI：
10.1101/gad.4.9.1623
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发表时间：
1990-09-01
影响因子：
10.5
通讯作者：
LEE, DN
中科院分区：
文献类型：
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作者：
LANDICK, R;STEWART, J;LEE, DN
在暂停和终止位点控制转录在细菌中是常见的。许多转录暂停和终止事件被认为是响应于新生转录物中RNA发夹的形成而发生的。β中的一些突变-赋予对转录抑制剂利福平抗性的大肠杆菌RNA聚合酶的亚基也改变对转录暂停和终止信号的反应。在此，我们报道了不赋予利福平抗性的改变终止的突变的分离，并显示这种突变主要发生在β-内酰胺酶的有限区域中。亚基多肽一个区域在氨基酸残基500和575之间，其涵盖几乎所有已知的利福平耐药突变的位置。许多改变终止的突变也发生在两个其它区域：在氨基酸残基740和840之间以及在β-半胱氨酸的羧基末端附近。亚基（氨基酸残基1225-1342）。β-半乳糖苷酶的这三个区域中的氨基酸序列亚基在原核和真核之间是保守的β-亚基同源物。在体外改变转录终止的几个突变影响在原核和真核RNA聚合酶β中相同的氨基酸残基。亚基同源物，这表明它们改变了多亚基RNA聚合酶共同的重要功能。我们建议β-γ的这三个区域在一些实施方案中，这些亚基可以接触转录复合物中的新生RNA转录物、RNA-DNA异源双链体或DNA模板，并且这些区域中的突变通过影响这些接触来改变转录暂停和终止。
Control of transcription at pause and termination sites is common in bacteria. Many transcriptional pause and termination events are thought to occur in response to formation of an RNA hairpin in the nascent transcript. Some mutations in the .beta.-subunit of Escherichia coli RNA polymerase that confer resistance to the transcription inhibitor rifampicin also alter the response to transcriptional pause and termination signals. Here, we report isolation of termination-altering mutations that do not confer rifampicin resistance and show that such mutations occur predominantly in limited regions of the .beta.-subunit polypeptide. One region is between amino acid residues 500 and 575, which encompasses the locations of almost all known rifampicin-resistance mutations. Many termination-altering mutations also occur in two other regions: between amino acid residues 740 and 840 and near the carboxyl terminus of the .beta.-subunit (amino acid residues 1225-1342). Amino acid sequences in these three regions of the .beta.-subunit are conserved between prokaryotic and eukaryotic .beta.-subunit homologs. Several mutations that alter transcription termination in vitro affect amino acid residues that are identical in prokaryotic and eukaryotic RNA polymerase .beta.-subunit homologs, suggesting that they alter an important function common to multisubunit RNA polymerases. We propose that these three regions of the .beta.-subunit may contact the nascent RNA transcript, the RNA-DNA heteroduplex, or the DNA template in the transcription complex and that mutations in these regions alter transcription pausing and termination by affecting these contacts.