Entamoeba histolytica: Structural and functional analysis of the Ehadh112 gene promoter

The Entamoeba histolytica Ehcp112 and Ehadh112 genes that encode the EhCPADH complex are separated by a non-coding 188 pb region. Their proximity suggests a coordinated expression regulation for both genes. Here, we studied the structure and function of 996 bp (p996CAT) upstream the ATG start codon of the Ehadh112 gene. The p996CAT plasmid drove CAT transcription with a 78% of the activity showed by actin promoter. Deletion of 330 bp at the 5′ end of p966CAT to produce the p776CAT plasmid, decreased activity to 40% in relation to actin promoter and to 50% of p996CAT, suggesting the presence of a silencer in this region. Interestingly, deletion of other 297 bp to the p776CAT to generate the p469CAT plasmid, augmented activity in 2.5-fold compared with p776CAT construction, showing the presence of a proximal enhancer promoter. Transcription initiation sites (−69 and −150 bp), TATA like box, GAAC, and Inr elements, as well as putative DNA binding motifs, were mapped in the −1 to −469 bp core promoter region.