A Nosy Neighbor: Purification and Functional Characterization of Lpg2149

Abstract

Ubiquitination is a process that marks proteins for various cell-signaling pathways, namely protein degradation and other processes. Th ese pathways are essential in a wide array of cellular processes, including defense mechanisms against invading pathogens. Th e ubiquitination process is universally found in all eukaryotic organisms, including plants and animals, and thus plays a vital role in cellular homeostasis. Recently, more discoveries have been made on prokaryotic eff ector proteins that hijack the ubiquitination system even when they do not possess a ubiquitin system of their own. MavC, also known as lpg2147 (Gan, Nakayasu, Hollenbeck, & Luo, 2019; Puvar et al., 2020; Valleau et al., 2018), has been found to be a ubiquitinating enzyme that ubiquitinates UbE2N by bypassing the usual E1, E2, E3 ubiquitination pathway. MavC plays an important role in the infection of Legionella pneumophila, which is the culprit of Legionnaires’ disease. Th rough earlier molecular biology analysis, it has been discovered that a neighboring gene on the same locus as MavC encodes lpg2149, which has been characterized to inhibit MavC’s function. Given the novelty of this protein, this research project aims to achieve cloning, expression, and purifi cation of lpg2149 so that in its inhibitory complex lpg2149 can be captured by X-ray crystallography. An attempt was made to crystallize and obtain the structure of lpg2149 with MavC. With the optimization of lpg2149 production demonstrated in this project, a better understanding of L. pneumophila pathogenesis can be obtained, which would help in our understanding of regulating L. pneumophila infection.