Our research is directed towards understanding the mechanisms involved in the control of the cell cycle in E.coli, particularly those involved in regulating initiation of replication and DNA segregation .

Initiation of DNA replication is very tightly controlled in bacterial cells being geared to the growth rate and nutritional conditions. It is known that DNA methylation is involved in regulating the frequency of initiation of replication in E.coli, an effect mediated by binding of a protein termed SeqA to hemimethylated DNA. We are using various genetic approaches to identify other proteins that co-operate with SeqA in this process. By defining the machinery involved, we hope to uncover new targets for interfering with cell growth.

We have developed novel methods for visualizing DNA segregation in bacterial cells, using green fluorescent protein, which allow us to record the behaviour of single DNA molecules in living cells. We are using similar approaches to study the mechanism of segregation of the F factor in E.coli with the aim of understanding how polarity is achieved in the bacterial cell. One of the F factor proteins involved in segregation of DNA is an ATPase termed SopA, which we have found forms a regular helical array extending from one cell pole to the other. Another protein, known to form such a structure, is the actin homologue, MreB which is thought to be involved in shape determination in E.coli. Given the similarities in structures formed by the two proteins, we are investigating MreB as a cellular factor which might have a role in DNA segregation.

Another area of interest is understanding the mechanisms by which bgl (beta-glucoside utilization) operon expression is regulated in E.coli. This operon is normally silent in wild type cells grown under laboratory conditions , but is activated in vivo in mice by unkown mechanisms. Several factors are involved in bgl silencing, including the global DNA binding protein H-NS and others not yet identified. Our interest is to use genetic and biochemical approaches to define all of the silencing factors involved and to use this information to identify the environmental factors in the mouse that lead to de-silencing. Our aim is to gain a better understanding of host-pathogen interactions through analysis of this model system.