Mycobacterium tuberculosis is the cause of tuberculosis in humans, a disease that affects over a one-third of the world's population. This slow-growing pathogen has only one ribosomal RNA operon, thus making its transcriptional apparatus a fundamentally interesting target for drug discovery. NusA binds to RNA polymerase and modulates several of the ribosomal RNA transcriptional processes. Here, we report the crystal structure of NusA, and reveal that the molecule consists of four domains. They are organised as two distinct entities. The N-terminal domain (residues 1 to 99) that resembles the B chain of the Rad50cd ATP binding cassette-ATPase (ABC-ATPase) and a C-terminal module (residues 108 to 329) consisting of a ribosomal S1 protein domain followed by two K homology domains. The S1 and KH domains are tightly integrated together to form an extensive RNA-binding structure, but are flexibly tethered to the N-terminal domain. The molecule's surfaces and architecture provide insights into RNA and polymerase interactions and the mechanism of pause site discrimination. They also allow us to rationalize certain termination-defective and cold shock-sensitive mutations in the nusA gene that have been studied in Escherichia coli.
|Number of pages||9|
|Journal||Journal of Molecular Biology|
|State||Published - Dec 14 2001|
Bibliographical noteFunding Information:
The authors thank Valerie Ennis-Adeniran and Nishi Vasisht for excellent technical assistance and the staff of the ESRF, Grenoble, for the provision of synchrotron data-collection facilities. This work was supported in part by the European Community for research, technological development and demonstration activities, Fifth Framework programme (Contract EU-Cluster QLK2-2000-01761). We thank Drs T. Terwilliger, S.J. Smerdon, W. Taylor and A. Ramos for technical advice and helpful suggestions on the manuscript.
- Crystal structure
- Mycobacterial growth
ASJC Scopus subject areas
- Structural Biology
- Molecular Biology