Award details

The general stress response of Bacillus subtilis

Reference	BB/D000521/1
Principal Investigator / Supervisor	Dr Richard Lewis
Co-Investigators / Co-Supervisors
Institution	Newcastle University
Department	Inst for Cell and Molecular Biosciences
Funding type	Research
Value (£)	280,645
Status	Completed
Type	Research Grant
Start date	01/12/2005
End date	30/11/2008
Duration	36 months

Abstract

Protein-protein recognition and post-translational modification of proteins play pivotal roles in a vast array of biological processes. Understanding the mechanism by which macromolecular complexes assemble and the structural consequences of phosphorylation are thus of fundamental importance. We aim to investigate molecular characteristics of the proteins involved in perceiving and transducing environmental stress in B. subtilis. The most significant of our objectives is the aim to determine the three-dimensional structure of a complex structure that is unprecedented in size in bacteria, that we term the stressosome. We will use two complementary techniques in parallel in our analysis, X-ray crystallography and cryo electron microscopy. In recent years, these have been used in combination to map individual components into larger structural frameworks, for instance the ribosome. We aim to dock the individual domains of the constituents of the stressosome into EM-derived molecular envelopes. The combination of protein crystallography and electron microscopy to determine structures of large macromolecular complexes and machines is still relatively new, and therefore our results will be of interest to the wider structural biology community. Simultaneously we will pursue the challenging X-ray crystal structure of the same macromolecular complex, for which crystals are already available.

Summary

The stress response of the bacterium Bacillus subtilis and its close relatives provides the cell with a protective mechanism against a wide range of chemical and physical insults. This research proposal concerns the proteins that regulate the activity of the molecular machine, RNA polymerase, which is required to initiate the expression of greater that one hundred genes that together act to provide the cell with its resistance against the imposed stress. Key to the information-processing pathway that indicates to the cell deterioration in its environment is a large structure called the stressosome. The stressosome is composed of several proteins that are closely related to a molecule called RsbR, and these act in concert in the signalling system that ultimately activates RNA polymerase. It is not known whether one type of stressosome exists, made of all the RSbR-related proteins, thus responsive to all types of stress, or whether there are multiple forms of the stressosome, each comprising just one of these RsbR-related proteins, which only respond to single, highly specific chemical cue. We aim to determine that structure of the stressosome at a molecular level, so that a better understanding of its function can be obtained. We will also investigate how stressosomes are assembled, and whether just single, or multiple, forms of it exist. This part of the study will provide information on the precise signaling mechanism(s) that the cell's response to stress is dependent upon. Because a constituent of the stressosome is closely related to the molecule that senses oxygen levels in blood, we believe that one of the functions of the stressosome is to sense fluctuations in concentrations of chemicals in the cell that accompany the imposition of stress. However, the identities of these chemicals are unknown and we aim to identify what these may be.

Committee	Closed Committee - Biomolecular Sciences (BMS)
Research Topics	Microbiology, Structural Biology
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

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