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GreA-induced transcript cleavage is accompanied by reverse translocation to a different transcription complex
1Department of Biology, Washington University, St. Louis, Missouri 63130.
The Journal of Biological Chemistry
|September 2, 1994
Summary
GreA and GreB factors induce transcript cleavage, causing Escherichia coli RNA polymerase to move backward on DNA without NTPs. This movement reveals heterogeneous transcription complex structures at different DNA positions.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Transcriptional regulation involves dynamic changes in RNA polymerase (RNAP) conformation.
- GreA and GreB are essential factors that can stimulate transcript cleavage by RNAP.
- RNAP translocation along DNA is a fundamental process in transcription.
Purpose of the Study:
- To investigate the structural conformations of transcription complexes during GreA-induced reverse translocation.
- To determine if transcript cleavage-mediated backtracking results in heterogeneous RNAP-DNA interactions.
Main Methods:
- Examined transcription complexes halted at specific DNA positions (+16 and trpL pause site).
- Analyzed structures before and after GreA treatment using transcript cleavage assays.
- Assessed changes in DNA footprint and transcription bubble size.
Main Results:
- Halted transcription complexes showed resistance to transcript cleavage after removing 6-10 nucleotides.
- During cleavage-induced reverse translocation, downstream RNAP-DNA contact moved minimally.
- Upstream DNA contact and transcription bubble borders moved with the 3'-end of the transcript.
Conclusions:
- GreA-induced transcript cleavage leads to heterogeneous RNAP-DNA complex structures.
- The observed backward movement of RNAP is consistent with discontinuous translocation models.
- These findings differ from previously reported movements of arrested RNA polymerase II complexes.