COMPARATIVE GENOMIC STUDY OF TRANSPOSABLE ELEMENTS IN TWO VIRULENT STRAINS OF Entamoeba histolytica

LOPEZ-ARIAS L; CALER E; PAOLETTA M; LORENZI H; GARBOSSA G.; FARBER MD

Mar del Plata

Congreso; X Congreso de Protozoología y Enfermedades Parasitarias; 2014

Sociedad Argentina de Protozoología

Entamoeba histolytica is the parasite that causes dysentery and liver abscesses in humans. However, most infections are asymptomatic. Several strains were isolated from feces (E. histolytica Rahman), liver (E. histolytica HM3:IMSS (HM3)) and bowel (E. histolytica HM1:IMSS (HM1)). E. histolytica contains many Transposables Elements (TE) among which are the non-Long Terminal Repeats retroelements: Long and Short Interspersed Elements (LINEs and SINEs). TE can give rise to the appearance of different virulent phenotypes by changing the expression of adjacent genes. In this context, our goal is to analyze the distribution of TE in the genomes of HM3 and HM1 and to assess their impact on the expression of genes involved in pathogenicity mechanisms. Our mapping of TE showed that the abundance of LINEs (HM3: 876; HM1: 1879 copies) was greater than that of SINEs (HM3: 354; HM1:867 copies). LINE1 (subtype of LINE) was the most frequent LINE: 56.2% (493/876) in HM3 and 49.7% (934/1879) in HM1. The full coverage (percentage of the corresponding length of the assembled genome) of LINEs was 1.38% in HM3 and 10.00% in HM1. To estimate the potential impact of TE on gene expression we defined a criterion of TE-gene association, where any coding sequence (CD) within 1 kb of a nearby TE is computed as associated and potentially modulated by that element. This analysis revealed that LINEs were slightly more frequently associated to CDs (HM3: 74.6%; HM1: 52.2%) than SINEs (HM3: 73.1%; HM1: 48.9% Subsequently, we performed a functional categorization of associated genes based on GO terms, in order to reveal the relatedness of TE insertions to functional categories. This analysis showed that kinase and binding proteins were preferentially associated with both SINEs and LINEs. These preliminary results indicate that the proposed in silico strategy will help in the identification of candidate genes for functional assays to elucidate novel virulence mechanisms in E. histolytica.