共 28 条
Interactions of Escherichia coli σ70 within the transcription elongation complex
被引:21
作者:
Daube, SS
[1
]
von Hippel, PH
机构:
[1] Univ Oregon, Inst Mol Biol, Eugene, OR 97403 USA
[2] Univ Oregon, Dept Chem, Eugene, OR 97403 USA
来源:
关键词:
Escherichia coli RNA polymerase;
core and holo RNA polymerase;
sigma factor;
synthetic bubble-duplex elongation complexes;
D O I:
10.1073/pnas.96.15.8390
中图分类号:
O [数理科学和化学];
P [天文学、地球科学];
Q [生物科学];
N [自然科学总论];
学科分类号:
07 ;
0710 ;
09 ;
摘要:
ri functional transcription elongation complex can be formed without passing through a promoter by adding a complementary RNA primer and core Escherichia coli RNA polymerase in trans to an RNA-primed synthetic bubble duplex DNA framework. This framework consists of a double-stranded DNA sequence with an internal noncomplementary DNA "bubble'' containing a hybridized RNA primer. On addition of core polymerase and the requisite NTPs, the RNA primer is extended in a process that manifests most of the properties of in vitro transcription elongation. This synthetic elongation complex can also be assembled by using hole rather than core RNA polymerase, and in this study we examine the interactions and fate of the sigma(70) specificity subunit of the holopolymerase in the assembly process. We show that the addition of holopolymerase to the bubble-duplex construct triggers the dissociation of the sigma factor from some complexes, whereas in others the RNA oligomer is released into solution instead, These results are consistent with an allosteric competition between sigma(70) and the nascent RNA strand within the elongation complex and suggest that both cannot be bound to the core polymerase simultaneously. However, the dissociation of sigma(70) from the complex can also be stimulated by binding of the holopolymerase to the DNA bubble duplex in the absence of a hybridized RNA primer, suggesting that the binding of the core polymerase to the bubble-duplex construct also triggers a conformational change that additionally weakens the sigma-core interaction.
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页码:8390 / 8395
页数:6
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