Molecular Basis of Bacterial Formaldehyde Sensing

Abstract

Formaldehyde is a highly toxic molecule; despite this, it is produced in the cells of all living organisms as a by-product of metabolic pathways. Consequently, several pathways have evolved throughout life in order to detoxify cellular formaldehyde. These pathways need to be regulated within the cell and this study sets out to determine how these pathways are regulated in particular bacteria. Several approaches are taken to achieve this. Known or predicted transcription factors that regulate formaldehyde detoxification pathways from particular organisms are considered. These proteins are called FrmR (E. coli), HxlR1 (Bacillus subtilis), and HxlR2 (Bacillus Cereus). The transcription factors are cloned and purified using molecular biology techniques. The proteins are subject to biophysical characterisation i.e. size and secondary structure composition. Additionally, the X-ray crystal structure of HxlR2 is determined and significant progress is made towards determining the structure of FrmR. Interactions of these transcription factors towards their target DNA sequences are studied along with the effect that formaldehyde has on these interactions. A reporter system is constructed that enables the behaviour of FrmR to be studied in vivo. Residues that are likely to play important roles in DNA recognition by this regulator are identified. Additionally, this reporter system identifies a residue that is essential for formaldehyde sensing by this protein. Overall, some significant insights into how these transcription factors carry out their biological function are established.

Date of Award	31 Dec 2012
Original language	English
Awarding Institution	The University of Manchester
Supervisor	David Leys (Supervisor)