Functional characterization of four thermolysins present in Leptospira pathogenic species

Author(s)

Kamila Oliveira Nunes

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2021-02-12

Examining board members

Ângela Silva Barbosa; Marcia Regina Franzolin; Amane Paldês Gonçales; Marcos Bryan Heinemann; Rita de Cássia Ruiz

• Advisor: Ângela Silva Barbosa

Abstract

Leptospirosis, caused by pathogenic bacteria of the genus Leptospira, is a disease of medical and veterinary importance highly widespread worldwide. Currently, leptospires are classified into more than 300 serovars grouped into 64 distinct species (pathogenic and saprophytic). These spirochetes produce several proteases potentially capable of causing tissue damage. Today, we know that proteins present in the culture supernatant of pathogenic strains are able to degrade several host molecules including proteins from the extracellular matrix, the coagulation cascade and the complement system, contributing to the invasion and immune evasion processes. The analysis of the genomes of leptospires available led us to the identification of four thermolysins, present only in pathogenic species, encoded by the genes LIC13320, LIC13321, LIC13322 and LIC10715. Bearing in mind that enzymes of the thermolysin family are crucial factors in the pathogenesis of several diseases caused by bacteria and represent potential targets for therapeutic intervention, this project aimed to functionally characterize these Leptospira metalloproteinases. The four thermolysins of L. interrogans were obtained in recombinant form and the heterologous expression of the thermolysin encoded by LIC13322 of L. interrogans (pathogenic strain) was also carried out in L. biflexa (saprophyte strain). The results indicate that L. interrogans thermolysins are capable of degrading several proteins involved in the activation of the human complement system, as well as some proteins of the extracellular matrix, and should, therefore, assist the bacteria in the processes of immune invasion and evasion. The heterologous expression of LIC13322 in the saprophyte strain did not confer resistance to the serum, suggesting that thermolysins must have an additive role and a certain degree of specificity of action. (AU)

• FAPESP's process: 16/08997-2 - Functional characterization of four thermolysins present in pathogenic species of Leptospira
• Grantee: Kamila Oliveira Nunes
• Support Opportunities: Scholarships in Brazil - Doctorate