Identification of Leptospira interrogans virulence factors through comparative proteomic analysis.

Author(s)

Edson Galdino do Nascimento Filho

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2022-10-13

Examining board members

Ana Lucia Tabet Oller do Nascimento; Wagner Luiz Batista; Cristiane Rodrigues Guzzo Carvalho; Júlia Pinheiro Chagas da Cunha; Nilmar Sílvio Moretti; Patrícia Severino

• Advisor: Ana Lucia Tabet Oller do Nascimento; Daniel Carvalho Pimenta

Abstract

Leptospira is a genus of spirochete bacteria that includes free-living saprophytic or non-pathogenic species found in water or soil, and pathogenic species, which are the etiologic agents of leptospirosis. This disease is a zoonosis of global incidence, occurring mainly in tropical and subtropical countries. Leptospirosis can be asymptomatic or symptomatic with variable clinical conditions in humans. The virulence and pathogenicity determinants of leptospires still remain poorly understood. In view of this, we performed a global analysis of the proteins expressed in the saprophytic species, L. biflexa, to compare with the proteome of the pathogenic species, L. interrogans, available in the literature. From this comparative analysis, the main objective is to recognize the potential targets involved in virulence and pathogenesis of L. interrogans. A total of 2,327 proteins were identified by mass spectrometry in L. biflexa representing 64% of the predicted proteins in the genome of this saprophytic species. The proteins identified in both species showed some functional uniformity by the COG software. Approximately 80% of the proteins had subcellular locations defined by the PSORTb software, and 21% of the proteins showed signal peptides predicted by SignalP and LipoP softwares. The vitamin B complex metabolic pathways (B1, B2, B6, B7 and B9) were identified in both species of leptospires, whereas the B12 and sialic acid pathways were identified only in the pathogenic species. The orthologous and exclusive proteins in the two species of leptospires were also identified by the software Get Homologues. The orthologous proteins were later classified as low conserved and conserved. From these analyses, only low conserved and exclusive proteins to L. interrogans were selected to be better investigated according to the results obtained on biological function (COG), subcellular localization (PSORTb and CELLO) and export signal peptide (SignalP and LipoP), together with the analysis of structural domains by Pfam and SMART softwares. A total of 1,109 proteins were previously selected in L. interrogans. From this total, we selected 738 proteins with structural domains (108 low conserved and 93 unique) and 123 proteins without structural domains (59 low conserved and 64 unique). The latter were based exclusively on their locations as outer membrane proteins, extracellular proteins and proteins with no defined location. According to these criteria, we have 861 proteins selected as potential targets involved in the virulence of pathogenic leptospires. (AU)

• FAPESP's process: 18/06201-1 - Identification of virulence factors of Leptospira interrogans through comparative proteomics analysis
• Grantee: Edson Galdino Do Nascimento Filho
• Support Opportunities: Scholarships in Brazil - Doctorate