Bioinformatics analysis for structure and function of localization of lipoprotein system transporters in Vibrio parahaemolyticus

Abstract:

[Objective] Vibrio parahaemolyticus is an important zoonotic pathogen. Its localization of lipoprotein (Lol) system is responsible for the transport and localization of lipoproteins in this bacterium, which is closely related to its pathogenicity and drug resistance. Systematic bioinformatics analysis of the Lol system transporters is helpful to promote further research on pathogenesis and resistance mechanism of V. parahaemolyticus. [Methods] The basic properties, protein interactions and tertiary structures of Lol system transporters LolA-E and LolCD₂E of V. parahaemolyticus were investigated by bioinformatics analysis, combining with ExPASy online tools, SignalP 4.0 Server, TMHMM-2.0, STRING, SWISS-MODEL and other softwares. [Results] LolA and LolB were acidic hydrophilic proteins with signal peptide sites and no transmembrane region, while LolC and LolE were alkaline hydrophobic membrane proteins. LolCD₂E was an neutral hydrophobic membrane protein, and LolC-E and LolCD₂E had no significant signal peptide sites. Subsequent studies should add a signal peptide sequence in the recombinant expression vector of LolCD₂E protein, and combine with detergent treatment to ensure the protein expression and purification. Protein interaction network showed that the coding genes of five proteins LolA-E can co-express, and be responsible for the synthesis and transport of lipoprotein. LolA-E had close interaction with other outer membrane proteins such as BamA, Pal, MacB and CmeC. Tertiary structural homology modeling showed that V. parahaemolyticus and Escherichia coli had the similar structures in LolA and LolB proteins. And LolC-E contained the homologous structure of MacB protein, which gave Lol system an important function for consuming ATP to transport lipoproteins. Furthermore, this study found a conserved Hook structure in LolC and LolE of V. parahaemolyticus for the first tim, which is a key region for LolCD₂E complex to bind with LolA and transport lipoprotein. [Conclusion] This study provides an important data basis for the study of expression purification, structure and function of Lol system transporter in V. parahaemolyticus, and provides new targets for the subsequent research and development of new antibacterials.