EZGI EROGLU¹, SILVIA ARDISSONE¹, PATRICK VIOLLIER<sup>1

1</sup>Department of Microbiology and Molecular Medicine, University of Geneva, 1211 Geneva 4, Switzerland

C. crescentus divides asymmetrically into two functionally specialized daughter cells: the motile non-capsulated swarmer cell and the non-motile and capsulated stalked cell. While the former resides in G1-like quiescent state, the latter is engaged in S-phase. In order to replicate, swarmer cells have to differentiate into stalked cells. Cell cycle studies in C. crescentus revealed that daughter cell-specific programs are implemented by conserved transcriptional activators and repressors that induce developmental and morphological transitions at key times, as in eukaryotic cells. For example, we found that expression of HvyA, a bacterial transglutaminase-like cysteine protease that prevents capsulation in swarmer cells, is activated by the G1-specific cell cycle transcriptional module.
In the effort to uncover new cell cycle regulated factors, I identified a previously uncharacterized gene (named camR for capsulation and motility Regulator) that regulates motility and capsulation. Although the camR transcript is abundant in G1-phase, I found that overexpression of CamR causes constitutive capsulation and reduced swarming motility. Moreover, my preliminary results showed that constitutive capsulation is due to a block in hvyA translation which is a bacterial transglutaminase-like cysteine protease (BTLCP) that prevents capsulation in swarmer cells. Interestingly, CamR also affects translation of other G1-specific genes, and therefore may represent a new cell cycle-dependent translational regulator in C. crescentus.
Bipolar localization of CamR-GFP points that in addition to temporal, CamR has spatial regulation. The polar localization pathway of CamR will be investigated further.