The interaction of two novel putative proteins of Leptospira interrogans with E-cadherin, plasminogen and complement components with potential role in bacterial infection

Abstract

Leptospirosis is a worldwide zoonosis caused by pathogenic species of Leptospira. Leptospires are able to adhere to exposed extracellular matrix in injured tissues and, once in the bloodstream, can survive the attack of the immune system and spread to colonize target organs. In this work, we report that two novel putative proteins, coded by the genes LIC11711 and LIC12587 of L. interrogans serovar Copenhageni are conserved among pathogenic strains, and probably exposed in the bacterial surface. Soluble recombinant proteins were expressed in Escherichia coli, purified and characterized. Both recombinant proteins bound to laminin and E-cadherin, suggesting an initial adhesion function in host epithelial cells. The recombinant protein LIC11711 (rLIC11711) was able to capture plasminogen (PLG) from normal human serum and convert to enzymatically active plasmin (PLA), in the presence of PLG activator. rLIC12587 (recombinant protein LIC12587) displayed a dose dependent and saturable interaction with components C7, C8, and C9 of the complement system, reducing the bactericidal effect of the complement. Binding to C9 may have consequences such as C9 polymerization inhibition, interfering with the membrane attack complex formation. Blocking LIC11711 and LIC12587 on bacterial cells by the respective antiserum reduced leptospiral cell viability when exposed to normal human serum (NHS). Both recombinant proteins could be recognized by serum samples of confirmed leptospirosis, but not of unrelated diseases, suggesting that the native proteins are immunogenic and expressed during leptospirosis. Taken together, our data suggest that these proteins may have a role in leptospiral pathogenesis, participating in immune evasion strategies.

Heterologous Expression of the Pathogen-Specific LIC11711 Gene in the Saprophyte L. biflexa Increases Bacterial Binding to Laminin and Plasminogen

“…LIC11711 has its amino acid coding sequence conserved among other pathogenic species, with an identity above 96%, according to BLASTp alignment [ 25 ]. The combination of a strong constitutive gene promoter with a target gene that is poorly expressed is a strategy used to increase its heterologous expression in Leptospira spp.…”

“…This operon codes for two hybrid signaling proteins: LvrA (LIC11709) and LvrB (LIC11708), which are only present in the pathogenic species of Leptospira [ 24 ]. The LIC11711 has its amino acid coding sequence conserved among other pathogenic species, with an identity above 96%, according to the BLASTp alignment [ 25 ]. The transcript level of this gene is higher in the virulent L. interrogans strain FIOCRUZ L1-130 compared with the culture-attenuated L. interrogans strain M20 [ 25 ].…”

“…The LIC11711 has its amino acid coding sequence conserved among other pathogenic species, with an identity above 96%, according to the BLASTp alignment [ 25 ]. The transcript level of this gene is higher in the virulent L. interrogans strain FIOCRUZ L1-130 compared with the culture-attenuated L. interrogans strain M20 [ 25 ]. The lic11711 gene of L. interrogans serovar Copenhageni was cloned and the protein expressed in Escherichia coli .…”

“…The recombinant protein was characterized in vitro as a surface protein and expressed during bacterial infection. The recombinant protein rLIC11711 was capable to interact with several ECM components, cellular receptors, fibrinolytic molecules, and components of the complement system, including Plg/Pla and Lam [ 25 ]. It seems that this protein has the potential to contribute to host-pathogen interactions in pathogenic Leptospira and therefore we decided to further investigate these functions in a bacterial cell system.…”

Licorice-Yuanhua Herbal Pair Induces Ileum Injuries Through Weakening Epithelial and Mucous Barrier Functions: Saponins, Flavonoids, and Di-Terpenes All Involved

“…Plasminogen (PLG) and keratin (KRT1) proteins are expressed in epithelial cells and are important in bacterial infection pathways (Baker et al, 2019;Kochi et al, 2019). Keratin proteins are distributed on the epithelial cell surface and provide anchor points for bacteria adhesion and colonization (Martinez-Rossi et al, 2017).…”