Award details

Determination of a new functional state of a multisubunit RNA polymerase

Reference	BB/C504700/1
Principal Investigator / Supervisor	Professor Xiaodong Zhang
Co-Investigators / Co-Supervisors	Professor Martin Buck, Dr Ardan Patwardhan, Professor Marin Van Heel
Institution	Imperial College London
Department	Biological Sciences
Funding type	Research
Value (£)	315,253
Status	Completed
Type	Research Grant
Start date	01/02/2005
End date	31/01/2008
Duration	36 months

Abstract

Gene transcription is an essential step in converting genetic information to proteins which carry out biological functions within all living organisms. Transcriptional regulations are often the final players of sophisticated signalling pathways that impact upon RNA polymerase activity. Recent progress had led to a great increase in the amount of structural information for the transcription machinery. The next challenge is to use this information to understand how genes are regulated and how transcription is initiated. Transcription activators/repressors and sigma factors together with the multisubunit RNA polymerase form the transcription regulatory machinery. The main objectives in this study are to address the gene regulation and initiation issue by studying the bacterial transcription regulation machinery. In particular, we plan to determine the organisation of the system containing the RNA polymerase, the sigma factor and a transcription activator at the point of DNA opening and analyse important protein-protein interactions. This functional state exists at the point of DNA melting, represents an activated state of transcription initiation and transition state from closed to open complex formation, only available for RNAp/sigma54 holoenzyme, at the point of ATP hydrolysis of the activator. This functional state is technically inaccessible for RNA/sigma70 holoenzyme which melts DNA spontaneously. We plan to use cryo-electron microscopy and single particle analysis methods top obtain a three-dimensional reconstruction of the functional complex. We also plan to use X-ray crystallography to analyse the complex between sigma factor and an activator protein. Combining the high and intermediate resolution structures proposed here and those already available, a quasi-atomic model of the RNAp/sigma54/Activator complex assembled around promoter DNA will be obtained. Furthermore, by comparing the structures of RNAp/sigma54 with and without the activator bound, structural changes in sigma54 and RNAp that eventually lead to open complex formation will be revealed. The structural information will complement those obtained from RNAp/sigma70/DNA complex, explaining the differences in terms of promoter recognition (-35 and ¿10 region for sigma70 while ¿24 and ¿12 regions for sigma54) and open complex formation and advance our understanding in bacteria gene transcription.

Summary

unavailable

Committee	Closed Committee - Biomolecular Sciences (BMS)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

I accept the terms and conditions of use (opens in new window)

export PDF file

back to list new search