Executive Summary : | Transporter proteins are the channels contributing to the influx or efflux of substances within or across the bacterial cell membranes. These may be located in the outer membrane, inner membrane, and periplasmic spaces. The transporter classification database (TCDB) has a collection of structurally or functionally characterized transport proteins from a diverse range of organisms (Ren and Paulsen, 2005; Saier et al., 2014). TCDB classified transporter proteins into (1) channels or pores, (2) electrochemical potential driven transporters, (3) primary active transporters, (4) group translocators, (5) transmembrane electron carriers, (8) accessory factors involved in transport, and (9) incompletely characterized Transport Systems (Saier et al., 2002). The first class includes small or large channels spanned across the membrane and providing transport of substances without the involvement of any energy or carriers. The second class is also known as secondary transporters and provides facilitated transport coupled with energy. The third class or primary active transporters involve the expenditure of primary energy sources driven by ATP, NADPH, or ions. Group translocators consist of transporter proteins coupled to enzymes allowing the modification of substrate before transport (Saier et al., 2016). Many transporter proteins contributing to pathogenesis also have some primary metabolically relevant functions. Their role in pathogenesis is result of evolutionary changes and adaptation of bacteria to the changing environment (Saier et al., 2016). Pathogenic bacterial strains when compared to non-pathogenic one has shown specialized proteins such as pore-forming toxins and membrane proteins related to virulence, nutrient uptake porters, and specialized iron scavengers (Tang & Saier, 2014). There have been many comparative studies reported in previous years to explain the evolution of proteins. A comparison of ribosomal proteins from 66 different species has shown their distribution among archaea, eukarya, and bacteria, and described a reductive evolution of these proteins (Lecompte et al., 2002). A cross comparative analysis of E. coli K-12, a non-pathogenic strain, and 6 pathogenic strains helped to identify the transporter proteins with specialized functions to contribute to the pathogenicity of infection-causing strains of the bacterium (Tang and Saier; 2014). Phylogenetic analysis of outer membrane pore-forming proteins from the bacterial and organellar outer membrane has shown the organization of these proteins and gene duplication events (Reddy et al., 2016). However, these studies need to be expanded to other infectious bacterial species to increase the knowledge about the role of transporter proteins in pathogenicity. In the present study, PIs are also aiming to find out the sequence and structural differences in transporter proteins from pathogenic and non-pathogenic strains of the deadliest infection-causing bacterial species. |