TRANSPORTER PROTEINS INTERACTIONS IN EXPORTING M. TUBERCULOSIS KEY VIRULENCE LIPID (PDIM)
Abstract
There are several virulence factors that strongly contribute to the ability of Mycobacterium tuberculosis to cause disease and highly resist the host defence mechanisms making it the most successful pathogen in the world. It has a complicated cell wall highly rich in lipids that assist in MTBs virulence in vivo. Phthiocerol dimycocerosate (PDIM) is a polyketide lipid that is the first virulence factor to be identified. Several studies conducted on PDIM transportation from where it is synthesized in the cytosol to the cell wall outer membrane found out the important role of Mmpl7 (protein from the RND permeases) in the localization process. Loss of Mmpl7 in M. tuberculosis showed piling up of PDIM inside of the mycobacterial cell and it was attenuated when tested in vivo. DrrC protein that is a part of DrrABC transporter complex was also shown to be essential in the transport of PDIM. However, it is still unknown if DrrA and DrrB are needed in localizing the PDIM on the cell surface. Furthermore, the possibility of a complex formed by two or all three Drr proteins in order to transport the PDIM molecule is yet to be investigated along with the possibility of Mmpl7 joining to form a larger complex. Here we demonstrate our experimental approaches to investigate these hypotheses to gain additional knowledge about PDIM transportation which can open many doors to eliminate this pathogen and produce new treatments and strategies to fulfil the hopes in an M. tuberculosis free world. There are several techniques used in this paper;; homologous recombination to generate the knockout mutants, lipid extraction to separate the cell wall lipids and free cellular lipids, TLC for lipid analysis and finally yeast two hybrids method to investigate protein interactions.