A Novel Leptospira interrogans Protein LIC13086 Inhibits Fibrin Clot Formation and Interacts With Host Components

Abstract

Leptospirosis is a neglected zoonosis, caused by pathogenic spirochetes bacteria of the genus Leptospira. The molecular mechanisms of leptospirosis infection are complex, and it is becoming clear that leptospires express several functionally redundant proteins to invade, disseminate, and escape the host’s immune response. Here, we describe a novel leptospiral protein encoded by the gene LIC13086 as an outer membrane protein. The recombinant protein LIC13086 can interact with the extracellular matrix component laminin and bind plasminogen, thus possibly participating during the adhesion process and dissemination. Also, by interacting with fibrinogen and plasma fibronectin, the protein LIC13086 probably has an inhibitory effect in the fibrin clot formation during the infection process. The newly characterized protein can also bind molecules of the complement system and the regulator C4BP and, thus, might have a role in the evasion mechanism of Leptospira. Taken together, our results suggest that the protein LIC13086 may have a multifunctional role in leptospiral pathogenesis, participating in host invasion, dissemination, and immune evasion processes.

A Review on Host-Leptospira Interactions: What We Know and Future Expectations

“…In the last few years, several proteins experimentally described as located on the Leptospira surface have been identified as plasminogen-binding. Interactions have been demonstrated to occur mainly via the lysine residues in proteins and plasminogen kringle domains, since the interactions were inhibited by a lysine analog, as observed by in vitro assay ( Domingos et al., 2012 ; Teixeira et al., 2015 ; Fernandes et al., 2016b ; Vieira and Nascimento, 2016 ; Pereira et al., 2017 ; Passalia et al., 2020a ; Passalia et al., 2021 ). Among many proteins already identified as a plasminogen receptor, the major outer membrane lipoproteins LipL32, LipL21 and LipL41 and the transmembrane protein OmpL1 are included ( Fernandes et al., 2012 ; Vieira et al., 2010 ; Takahashi et al., 2021 ).…”

“…Leptospira associated with plasmin have the capacity to cleave ECM proteins and degrade complement components, such as C3b and IgG, interfering with the deposition of these molecules on the bacterial surface and consequently disrupting the opsonophagocytosis process, which facilitates bacterial immune evasion (Figure 1) (Vieira et al, 2009;Vieira et al, 2011;Vieira et al, 2013;Verma et al, 2020) In the last few years, several proteins experimentally described as located on the Leptospira surface have been identified as plasminogen-binding. Interactions have been demonstrated to occur mainly via the lysine residues in proteins and plasminogen kringle domains, since the interactions were inhibited by a lysine analog, as observed by in vitro assay (Domingos et al, 2012;Teixeira et al, 2015;Fernandes et al, 2016b;Vieira and Nascimento, 2016;Pereira et al, 2017;Passalia et al, 2020a;Passalia et al, 2021). Among many proteins already identified as a plasminogen receptor, the major outer membrane lipoproteins LipL32, LipL21 and LipL41 and the transmembrane protein OmpL1 are included (Fernandes et al, 2012;Vieira et al, 2010;Takahashi et al, 2021).…”

“…As reported for the bacteria, plasminogen bound to recombinant proteins is converted to active plasmin in the presence of an exogenous activator. Also, proteins such as rLIC11711, rLIC13259, Lsa24.9, rLIC13086 and LipL41 were able to acquire plasminogen from human serum, suggesting the viability of these interactions under physiological conditions and their possible role in leptospiral virulence ( Cavenague et al., 2019 ; Kochi et al., 2019 ; Rossini et al., 2020 ; Passalia et al., 2021 ; Takahashi et al., 2021 ). Leptospiral immunoglobulin-like proteins, known as Lig proteins, have also been identified as plasminogen-binding.…”

“…with fibrinogen is mediated by several outer membrane proteins. To date, the fibrinogen-binding proteins identified include: LigA and LigB ( Choy et al., 2011 ; Lin et al., 2011 ), OmpL37 ( Pinne et al., 2010 ), Lsa33, Lsa25, Lsa30 and OmpL1 ( Oliveira et al., 2013 ), Lsa23, Lsa36 ( Siqueira et al., 2013 ), Lsa37 ( Silva et al., 2016 ), rLIC10508 ( Siqueira et al., 2015 ), Lsa25.6 and Lsa16 ( Pereira et al., 2017 ), ErpY ( Ghosh et al., 2019 ), rLIC10774 ( Passalia et al., 2020a ), and rLIC13086 ( Passalia et al., 2021 ). The interactions with most of these proteins were found to be dose-dependent and specific.…”

“…Among these proteins, only LenA and EF-Tu showed the ability to inactivate C3b. The interaction with C4BP was demonstrated by Lsa30 ( Souza et al., 2012 ), rLIC10774 ( Passalia et al., 2020a ) and rLIC13086 ( Passalia et al., 2021 ), but only Lsa30 was assayed and shown to mediate C4b inactivation ( Souza et al., 2012 ). Several proteins were able to interact with both regulators and inactivate C3b and C4b, such as the LigA and LigB ( Castiblanco-Valencia et al., 2012 ), LcpA ( da Silva et al., 2015 ), enolase ( Salazar et al., 2017 ) and Lsa23 ( Siqueira et al., 2016 ; Siqueira et al., 2017 ).…”