Conjugation is the mechanism by which bacteria exchange genetic information. This process relies on the direct transfer of mobile genetic elements via a trans-membrane channel between the donor and the recipient cells. Although this mechanism has been extensively studied in gram-negative organism, very little in known on how this process takes place in their gram-positive counterpart. To address this important question in bacterial evolution, we use the tetracycline resistance plasmid pCW3 from Clostridium perfringens as study model. 

The pCW3 plasmid encodes series proteins necessary for the assembly the C. perfingens conjugation system similar to that of Type IV secretion system. Here, I will present the expression, purification and preliminary crystallographic analysis of proteins involved in the formation of the relaxosome. The relaxosome is the starting point for conjugation where specialized proteins recognize and process the DNA fragment prior to transfer. I will also present data on the coupling protein, which form an important component of the apparatus as it provides the motor force to propel DNA through the transmembrane channel.