[Show abstract][Hide abstract] ABSTRACT: The early branching eukaryote Entamoeba histolytica is a human parasite that is the etiologic agent of amebic dysentery and liver abscess. The sequencing of the E. histolytica genome combined with the development of an E. histolytica microarray has resulted in the identification of several distinct gene expression profiles associated with virulence. The function of many modulated transcripts is unknown and their role in pathogenicity is unclear. They however represent a pool of potential virulence factors that could be targets for the development of novel therapeutics. Efficient tools and methods to characterize these novel virulence-associated genes and proteins would be beneficial. Here we report the use of the Gateway((R)) cloning system to generate the E. histolytica expression vector pAH-DEST. To test the usefulness of this system, the vector was used to construct a plasmid containing a recombinant version of the locus EHI_144490, which encoded a protein of unknown function. The recombinant gene was expressed and the recombinant protein, which was strep-myc-tagged, showed a cytoplasmic localization in transfected trophozoites. This expression vector with the Gateway((R)) system should facilitate investigation into the functions of novel proteins in E. histolytica.
Full-text · Article · Oct 2008 · Parasitology International
[Show abstract][Hide abstract] ABSTRACT: The unicellular eukaryote Entamoeba histolytica is a human parasite that causes amebic dysentery and liver abscess. A genome-wide analysis of gene expression modulated by intestinal colonization and invasion identified an upregulated transcript that encoded a putative high-mobility-group box (HMGB) protein, EhHMGB1. We tested if EhHMGB1 encoded a functional HMGB protein and determined its role in control of parasite gene expression. Recombinant EhHMGB1 was able to bend DNA in vitro, a characteristic of HMGB proteins. Core conserved residues required for DNA bending activity in other HMGB proteins were demonstrated by mutational analysis to be essential for EhHMGB1 activity. EhHMGB1 was also able to enhance the binding of human p53 to its cognate DNA sequence in vitro, which is expected for an HMGB1 protein. Confocal microscopy, using antibodies against the recombinant protein, confirmed its nuclear localization. Overexpression of EhHMGB1 in HM1:IMSS trophozoites led to modulation of 33 transcripts involved in a variety of cellular functions. Of these, 20 were also modulated at either day 1 or day 29 in the mouse model of intestinal amebiasis. Notably, four transcripts with known roles in virulence, including two encoding Gal/GalNAc lectin light chains, were modulated in response to EhHMGB1 overexpression. We concluded that EhHMGB1 was a bona fide HMGB protein with the capacity to recapitulate part of the modulation of parasite gene expression seen during adaptation to the host intestine.