Abstract 2175 Phosphorylation State of the Intermediate Protein Partner RsbV1 Impacts Growth and Progeny Production of Chlamydia trachomatis

Chlamydia trachomatis is the most prevalent sexually transmitted bacterial infection worldwide, representing a major public health concern. This obligate intracellular bacterium has a phylum-defining biphasic developmental cycle whose regulatory signals and mechanisms are still poorly understood. One protein system that has been shown to govern the cycle's regulation is the Rsb system. This system works based on the phosphorylation state of an intermediate, RsbV1, which determines the activity of a periplasmic sensor phosphatase and a terminal protein partner kinase, RsbU and RsbW respectively. Although genetic disruption of RsbU has been shown to cause a dramatic decrease in progeny production, disruption of RsbW does not, making the Rsb system's role in C. trachomatis' development unclear. We examined the importance of RsbV1's phosphorylation state by studying the effect of its overexpression on progeny production and growth with a tetracycline inducible system. We also examined the overexpression of a phosphodeficient mutant for RsbV1, RsbV1S56A, and used immunofluorescent microscopy to determine effects on morphology and size. Induction between 16 and 24 hours post infection led to a significant decrease in progeny production with overexpression of both wildtype and phosphodeficient RsbV1. Furthermore, we found that expression of RsbV1S56A led to a significant reduction in inclusion size. Future studies with different induction periods will be performed to clarify the role of RsbV1's phosphorylation state in the system, which could provide a better insight on C. trachomatis' development and potential ways to address its public health impact. This project was supported by an Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under grant number P20 GM103418.