Functional analysis of species-specific genes that may contribute to Leishmania tropism

Genome sequencing of three Leishmania species (L.infantum, L.major and L.brazitiensis) that cause different types of leishmaniasis has identified only a few species-specific genes that may contribute to Leishmania tropism in the host. This thesis describes the preliminary analysis of four Leishmania infantum species-specific genes and the functional analysis of one selected gene from the preliminary analysis, LinJ31.3030, which codes for a putative phosphatase. Transgenic parasites deleted for this sequence have been generated by sequential gene replacement and these analyses have demonstrated the presence of four LinJ31.3030 alleles rather than the two expected for this diploid organism. These data correlate with recent deep sequencing of the L.infantum strain, suggesting that chromosome 31 might be tetrasomic in this and other species. In phenotypic analysis, the LinJ31.3030 deleted mutants demonstrated a reduced flagella length compared to the flagella of wild type promastigotes. In-depth bioinforrnatic analysis suggests that Linj31.3030 codes for a cofilin phosphatase. As reported for chronophin (the human cofilin phosphatase), recombinant Linj31.3030 protein has enzyme activity against a phospho-cofilin peptide. If the identification of Linj31.3030 as a cofilin phosphatase is verified, this enzyme may modulate the flagellar malfunction phenotype observed in Leishmania cofilin deletion mutants, impacting on parasite motility and infectivity.EThOS - Electronic Theses Online ServiceGBUnited Kingdo