Gene expression and micro-evolution in bacterial population

All living organisms rely on accessing the information in the genes contained in their chromosomes for survival. It is now becoming clear that even simple cells like those of bacteria are very well organised. The central dogma of biology – DNA is copied into RNA which is translated into protein – is now being underpinned by studies which seek to see how these key information flow processes relate to the detailed dynamic organisation and functioning of the cell. Little is known about the way in which the components of the RNA production apparatus are organised in living cells. With support from the Leverhulme Trust we will tackle this knowledge gap through looking at temporal and spatial organisations of key protein complexes that activate genes, the so-called transcription activator proteins. We plan to work out how one type of important small molecular machine that activates genes is organised on the chromosome of a living cell, and how this organisation changes with the complexity of the chromosome and whether or not the outcomes of the action of this machine is different between cells, as a possible source of heterogeneity and physiological diversity amongst cells in population.

We will use cutting edge live cell single molecule imaging methods to directly monitor the assembly of components of the gene expression apparatus, quantifying its outputs including determining the dynamics of the process to help establish the operating principles that underpin gene expression. So far this imaging approach has not been applied to the complex control system we will tackle. Moreover, since the system being studied involves the activities of membrane bound components which are hard to recapitulate in purified systems, gaining insights into how these classically challenging cellular features contribute to regulation is a reasonable expectation. We expect to gain insights into how many transcription factor molecules have assembled, where they assemble, how long they assemble for, where they move to and the impacts of their partner proteins on such characteristics. We will work out if their individual actions at single or multiple chromosomal sites lead to the same levels of gene expression or not, and deduce whether this can account for heterogeneity in gene expression between cells.

Professor Martin Buck, Dr Goran Jovanovic and Dr Liming Ying
Imperial College London

Martin was awarded a Research Project Grant in December 2012.

 Gene transcription and microevolution JPG