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Crystallization and preliminary X-ray diffraction studies on the N-utilizing substance A (NusA) from Mycobacterium
B Gopal1, K G Papavinasasundaram, M J Colston
1Division of Protein Structure, The National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, England.
Summary
Mycobacterium tuberculosis NusA protein, crucial for bacterial transcription, was successfully cloned, overexpressed, and crystallized. This structural study provides insights into its role as a DNA-dependent RNA polymerase cofactor.
Area of Science:
- Molecular Biology
- Structural Biology
- Microbiology
Background:
- N-utilizing substance A (NusA) is a vital protein cofactor for DNA-dependent RNA polymerase in eubacteria.
- NusA regulates transcription through elongation, pausing, termination, and antitermination complex formation.
- Its function involves binding to RNA polymerase core enzyme, other factors, and specific RNA sequences.
Purpose of the Study:
- To clone and overexpress the NusA protein from Mycobacterium tuberculosis.
- To obtain crystals of M. tuberculosis NusA for structural analysis.
- To facilitate high-resolution structural determination of M. tuberculosis NusA.
Main Methods:
- Cloning and overexpression of M. tuberculosis NusA in Escherichia coli.
- Protein purification and crystallization using the hanging-drop vapour-diffusion method.
- X-ray diffraction data collection to 1.7 A resolution.
Main Results:
- Successful cloning and overexpression of M. tuberculosis NusA.
- Crystallization of M. tuberculosis NusA in space group P3(1)21.
- Unit-cell parameters determined as a = b = 78.1 A, c = 180.3 A.
- A native data set complete to 1.7 A resolution was collected.
Conclusions:
- The study reports the successful structural characterization of M. tuberculosis NusA.
- The obtained crystal data enables detailed structural analysis of NusA.
- This structural information will aid in understanding NusA's role in transcription regulation.