Control of cellular asymmetry. Before they divide, Caulobacter cells are asymmetric with a flagellum at one pole and a stalk and holdfast at the other pole. We use genetic and molecular methods to identify genes that are involved in the maintenance of cellular asymmetry. We have identified mutants that have lost their cellular asymmetry and that synthesize a stalk and a holdfast at both poles of cells. Genes identified by this method include a sigma factor and a response regulator involved in a signal transduction pathway that couples polar development to cell division.
Adhesion is an important component of bacterial infections.
In Caulobacter, adhesion is mediated by the holdfast, a complex polysaccharide with strong adhesive properties found at the tip of the stalk. The stalk and holdfast are synthesized at the same pole of the cell during the same stage of the developmental program. Using genetic screens, we have identified genes required for holdfast export and attachment and we are studying their function. We are particularly interested in how the holdfast is localized to a specific pole of the cell. The recent completion of the genomic sequence of the Caulobacter genome provides new avenues to study the control of cell differentiation.