Abstract
Bacteria in the genus Chlamydia are obligate intracellular pathogens that infect a variety of eukaryotic species and impose a significant health burden worldwide. C. trachomatis can cause a wide range of genital infections and is the causative agent of trachoma, an ocular infection that can lead to blindness. All chlamydial species undergo a complex, multi cell form developmental cycle that is essential for proper amplification and dissemination of the infection. This cycle transitions between three major cell forms; elementary bodies (EBs) and non-replicative cell forms that invade the host by polymerizing actin residues for pathogen-facilitated endocytosis and forming a parasitophorous vesicle termed the inclusion. Once in the host, the EB hijacks host microtubule networks to migrate towards the host MTOC and golgi and germinates into the replicative reticulate body (RB) that amplifies the bacterial population within the inclusion. At ~14 hpi the RBs will begin to asymmetrically divide to produce one RB and one intermediate body (IB) transitions back to the EB over the course of ~8-10 hours. This cycle is essential for effective growth and proliferation of the bacteria but is not well understood.This dissertation seeks to further our understanding of a key player in chlamydial development the early upstream ORF (Euo) protein. Canonically, Euo is known as a master regulator of late (EB associated) gene repression to impede RBs from prematurely undergoing EB differentiation. By utilizing cell-form specific promoter reporters, ectopic expression, and Crispr-dCas12 Knockdown vectors we demonstrate that Euo is not impacting RB development or division. The data from these experiments suggest that Euo actually regulates a key division step in the early IB and is essential for proper IB-to-EB development.