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Crystal structure of the GreA transcript cleavage factor from Escherichia coli
C E Stebbins1, S Borukhov, M Orlova
1Rockefeller University, New York, New York 10021.
Nature
|February 16, 1995
Summary
The crystal structure of the transcription elongation factor GreA reveals a coiled-coil domain that directly interacts with RNA polymerase. This interaction is crucial for inducing transcript cleavage, enhancing RNA synthesis.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Transcription elongation factors enhance RNA polymerase activity.
- Factors like E. coli GreA and eukaryotic SII (TFIIS) induce transcript cleavage for improved RNA synthesis.
- Understanding the structural basis of GreA function is key to elucidating transcription regulation.
Purpose of the Study:
- To determine the high-resolution crystal structure of the transcription elongation factor GreA.
- To elucidate the structural mechanisms by which GreA interacts with RNA polymerase and mediates transcript cleavage.
Main Methods:
- X-ray crystallography was employed to determine the structure of GreA at 2.2 Å resolution.
Main Results:
- The GreA structure features an N-terminal antiparallel α-helical coiled-coil dimer, resembling that of seryl-tRNA synthetases.
- A functional site located at the tip of the coiled-coil 'finger' directly contacts the 3'-end of the RNA transcript.
- An asymmetric charge distribution within GreA suggests a specific interaction mode with the RNA polymerase elongation complex.
Conclusions:
- The crystal structure provides a molecular basis for GreA's role in transcript cleavage during transcription elongation.
- GreA's unique structural features facilitate its interaction with RNA polymerase, enabling the regulation of RNA synthesis.