CLONING AND CHARACTERIZATION OF AN UNUSUAL ELONGATION FACTOR-1-ALPHA CDNA FROM ENTAMOEBA-HISTOLYTICA

The coding sequence deduced from two overlapping cDNA inserts obtained from a pathogenic strain of Entamoeba histolytica revealed a striking homology (>85%) with elongation factor EF-1α from Saccharomyces cerevisiae and Artemia salina. The deduced amino acid sequence predicted a size of 49 kDa, and antibodies raised against the S. cerevisiae EF-1α cross-reacted with an amoebic protein of similar size (45-47 kDa). Sequence analysis of the cDNA revealed that the 5′ untranslated region contained a stretch of 190 nucleotides which was perfectly complementary to a segment of the 3′ terminal coding region situated 1015 bases downstream of the methionine initiation codon. Electron microscopy of self-renatured cDNA confirmed the potential of such molecules to form a stem-loop secondary structure. The presence of the complementary sequences was confirmed at the genomic level by sequence analysis of polymerase chain reaction-amplified segments which span both the 3′ and 5′ terminal complementary regions. Comparison of the deduced amino acid sequence of E. histolytica EF-1α with Ef-Tu from Escherichia coli and EF-1α from different sources, suggested that the major functional domains of the protein are located within the loop structure. © 1991.