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

Abstract

Leptospirosis is a febrile disease and the etiological agents are pathogenic bacteria of the genus Leptospira. The leptospiral virulence mechanisms are not fully understood and the application of genetic tools is still limited, despite advances in molecular biology techniques. The leptospiral recombinant protein LIC11711 has shown interaction with several host components, indicating a potential function in virulence. This study describes a system for heterologous expression of the L. interrogans gene lic11711 using the saprophyte L. biflexa serovar Patoc as a surrogate, aiming to investigate its possible activity in bacterial virulence. Heterologous expression of LIC11711 was performed using the pMaOri vector under regulation of the lipL32 promoter. The protein was found mainly on the leptospiral outer surface, confirming its location. The lipL32 promoter enhanced the expression of LIC11711 in L. biflexa compared to the pathogenic strain, indicating that this strategy may be used to overexpress low-copy proteins. The presence of LIC11711 enhanced the capacity of L. biflexa to adhere to laminin (Lam) and plasminogen (Plg)/plasmin (Pla) in vitro, suggesting the involvement of this protein in bacterial pathogenesis. We show for the first time that the expression of LIC11711 protein of L. interrogans confers a virulence-associated phenotype on L. biflexa, pointing out possible mechanisms used by pathogenic leptospires.

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

“…L. biflexa expressing LIC11711 on its surface showed increased binding to laminin and plasminogen compared to the wild-type or empty plasmid-containing strains. LIC11711-bound plasminogen was capable of being converted to plasmin in the presence of uPA ( Kochi et al., 2020 ), where this was the first time that a mutant was used to validate a leptospiral plasminogen receptor ( Figure 2 ).…”

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

“…Only lately, with the construction of shuttle vector E. coli-Leptospira and the use of CRISPR-Cas9 methodologies, we started to obtain either knock in and knock out mutants, respectively (Pappas and Picardeau, 2015;Fernandes et al, 2019;Fernandes and Nascimento, 2020;Fernandes et al, 2021). We succeeded in some cases with L. biflexa knock in mutants showing the gain of function similar to the ones observed with the in vitro studies with the protein LIC11711 (Kochi et al, 2020). Yet, we are encountering many difficulties, probably associated with the features of genes/proteins.…”