Cells can polarize in order to subcellularly localize structures and molecules and change shape, processes that in eukaryotes are largely governed by the actin cytoskeleton. Recently, MreB has been identified as a bacterial actin homolog that determines cell shape. The conservation of actin-like proteins suggests that prokaryotes and eukaryotes may share mechanisms governing cell polarity. Of the bacteria, Caulobacter crescentus is particularly well suited for the study of polarity. Cell cultures are easily synchronized and there are multiple morphological and molecular markers of asymmetry. Since joining the Shapiro lab, I have discovered that MreB localization dynamically changes. I have also established an in vitro MreB polymerization assay and begun characterizing several candidate MreB-interactors. In the future, I propose to continue these studies by investigating the role of MreB in determining Caulobacter cell polarity, further characterizing MreB dynamics both in vivo and in vitro, and exploring MreB signaling by identifying and characterizing MreB-interacting proteins. By examining such a simple cell biological system, I hope to gain insight into the most fundamental mechanisms of actin-based regulation and cell polarity.
