The Entamoeba histolytica genome: something old, something new, something borrowed and sex too?

Abstract

An ancient and potent pathogenEntamoeba histolytica is an intestinal protozoan parasite of humans that causes amebic colitis and amebic liver abscess: diseases associated with significant levels of morbidity and mortality worldwide [1]. The organism has a simple life cycle, existing as either the motile trophozoite or the infectious, hardy cyst form. Trophozoites of E. histolytica reside within the anaerobic confines of the human colon, lack mitochondria, derive energy from fermentation and reproduce by binary fission. E. histolytica trophozoites can be potent pathogens, possessing an armamentarium that includes a galactose-N-acetyl-galactosamine-binding lectin that mediates adherence to host cells, pore-forming proteins (amebapores) that can lyse bacteria or eukaryotic cells, cysteine proteinases that can cleave extracellular-matrix proteins and facilitate invasion into the colonic mucosa, and impressive phagocytic capabilities [1]. During the past three decades, the tools of molecular biology have greatly increased the understanding of E. histolytica pathogenesis. The recent publication of the E. histolytica genome by Loftus et al.[2] provides remarkable new insights into the biology of E. histolytica, helps understanding of the requirements for intestinal parasitism and sets the stage for a new, far more detailed understanding of this important pathogen.

Replacement of the essential Dictyostelium Arp2 gene by its Entamoeba homologue using parasexual genetics

“…Furthermore, despite their being no confirmed evidence of sex in Entamoeba , the sequenced genome reveals an almost complete complement of genes required for meiosis [42]. In light of this it is unclear why it is so difficult to achieve homologous recombination in this parasite.…”

The impact of genomics on population genetics of parasitic diseases

“…Population genetic studies of several parasite species have indicated that genetic exchange is likely to occur or has taken place evolutionarily recently in the species (see for example in T. vaginalis [18], Giardia [26] and other parasite species reviewed in [27]). In the enteric pathogen E. histolytica, analysis of the first reference genome revealed a complement of genes necessary for meiosis, pointing to the possibility of sex in natural populations [28]. However, more substantial evidence was not available until the generation of a large NGS dataset of ten lab-cultured lines from Mexico, Bangladesh, Italy, United Kingdom, Korea and Venezuela [29].…”

Amoebozoans are Secretly but Ancestrally Sexual: Evidence for Sex Genes and Potential Novel Crossover Pathways in Diverse Groups of Amoebae

“…1975; Schuster 1976; Dacks and Roger 1999a; Goldstein 1999a; Ramesh et al. 2005; Stanley 2005). However, the exact mechanism of sexual developments in most of these lineages is obscure or deviant from those observed in animals, fungi and plants (Lahr et al.…”