PUTATIVE SERINE THREONINE PROTEIN-KINASE EXPRESSED IN COMPLEMENT-RESISTANT FORMS OF ENTAMOEBA-HISTOLYTICA/

Entamoeba histolytica is susceptible to complement attack in its lumen -dwelling state and develops complement resistance during pathogenic t issue invasion. As experimental evidence suggests that this change in phenotype is accompanied by a change in gene expression, we constructe d a subtractive cDNA library to identify genes involved. Poly(A)(+)RNA from complement-sensitive trophozoites was subtracted from single str anded cDNA derived from complement-resistant ones. Transcripts enriche d in the library were found to code for a putative polypeptide compris ing all sequence elements characteristic for serine/threonine protein kinases. The gene contains an intron of 46 nucleotides and two polyade nylation sites. Northern-blot analyses confirmed that the gene is expr essed in both tissue-derived and laboratory-grown forms of complement- resistant E. histolytica.