Protein localization, cell division, and gene regulation
The bacterial cell is surprisingly complex in its organization. Many proteins are only found at specific regions within the cell, such as at the cell pole, or at the middle of the cell, where division takes place. Not much is known about how proteins are transported to the correct locations within the bacterial cell. We use the bacterium Bacillus subtilis as a model organism to study protein localization.
The localization of proteins is tightly linked to the positioning of the cell division septum. Although the main components of the division septum have been identified the mechanism of septum construction is basically unknown. We have discovered a cluster of conserved cell division proteins that appear to function in one of the late steps in septum synthesis. Since these proteins are conserved in Gram-positive bacteria we can compare the activity of these proteins between different species such as B. subtilis and the human pathogen Streptococcus pneumonia, to clarify their conserved functions.
Cellular differentiation and gene regulation
Bacteria are remarkably well equipped to survive adverse environmental conditions. For example, B. subtilis can differentiate into cells that become genetically competent and therefore are able to take up DNA, or, when the conditions are right, they can start to sporulate. A fascinating aspect of these differentiation processes is that they occur only in a subset of cells within the population. The complex gene regulation processes behind these heterogenic (bi-stable) differentiation processes is being investigated. In fact bi-stable gene regulation is a common aspect in both prokaryotic and eukaryotic development. Insights into the mechanisms of heterogenic differentiation in bacteria can also help us to understand why pathogenic bacteria tend to react differently to antibiotic treatments.