Evaluating protein-protein interactions of CpsA, a virulence factor in Group B Streptococcus

Streptococcus agalactiae, Group B Streptococcus (GBS), is an important human pathogen, causing life-threatening sepsis and meningitis in newborns. The virulence of GBS in part can be attributed to its ability to produce a polysaccharide capsule. CpsA has been recognized as an integral part of capsule synthesis as well as having a role in transcriptional regulation. We hypothesize that protein-protein interactions with CpsA play a role in virulence and may be required for CpsA function. Elucidating CpsA protein-protein interactions may provide a better understanding of CpsA function in the capsule synthesis pathway. Using a BACTH system we have confirmed that CpsA interacts with the CpsC protein. Interactions between CpsA and predicted partner CpsE were not supported while interactions between CpsA and CpsY may be transient. Our pull down did not find any of these proteins however, we have identified multiple additional proteins of interest, including FtsZ and CodY. Understanding protein-protein interactions of CpsA will help in new antimicrobial therapies targeting capsule synthesis.