Functional Characterization of Groel2 Protein as a Surface Adhesin of Mycobacterium Tuberculosis and its application in Targeted Delivery of Anti Tubercular Drugs

Abstract

Mycobacterium tuberculosis (M.tb) stands as a global health concern of prime importance. Tuberculosis (TB), the infection caused by M.tb, is a debilitating disease with very high morbidity and mortality rates. Conventional treatment of TB involves administration of multiple drugs over a prolonged period of 6 months. Most anti-TB drugs are associated with numerous side effects because of which patient compliance to the treatment is very poor. An effective novel strategy is necessary to deliver anti-TB drugs directly into infected macrophages so as to reduce the dosage and systemic toxic effects. Targeted nanoparticle mediated drug delivery systems offer ample scope in this regard. We aimed at delivering anti-TB drug rifampicin (RIF), through LOX-1 receptors into macrophages infected with mycobacteria. For this we have developed GroEL2 conjugated RIF loaded poly (lactic-co-glycolic acid (PLGA) nanoparticles (Gro-RIF-PLGA NPs) for targeting into macrophages infected with mycobacteria. To understand the molecular level interaction between the target receptor LOX-1 and the ligand GroEL2, we used computational methods. Protein-protein docking was carried out to infer the interactions between LOX-1 receptor and GroEL2 of M.tb at the molecular level. A stable protein-protein complex was formed by LOX-1 and GroEL2 with a binding energy of -15.5 kcal/mol. This complex was stabilized by hydrophobic interactions, electrostatic forces and hydrogen bonds. LOX-1 interacted with GroEL2 at the major ligand recognizing regions like the basic spine, central hydrophobic tunnel and saddle hydrophobic patch. Three main basic spine residues - R248, R231 and R229, were primarily involved in hydrogen bonds and electrostatic interactions with GroEL2. The peptide binding residues present in the apical domain of GroEL2 (F279, V262, V261, L257, Y197 and Y201) were involved in strong hydrophobic interactions with LOX-1 saddle hydrophobic residues F200, P201, A259 xi and L258. When docked along with poly inosinic acid (PIA) inhibitor, LOX-1-G