CLONING OF THE EH CDC2 GENE FROM ENTAMOEBA-HISTOLYTICA ENCODING A PROTEIN-KINASE P34CDC2 HOMOLOG

To understand better growth regulation in the protozoan parasite, Entamoeba histolytica (Eh), a homologue of the cdc2 gene encoding the yeast cyclin-dependent protein kinase, p34cdc2, has been cloned and sequenced. This gene, called Eh cdc2, contains a 79-bp intron located in the same place as the second of four introns in the Schizosaccharomyces pombe cdc2 gene. The sequence of an Eh cdc2 cDNA confirms the conserved eukaryotic splice donor (GT) and acceptor (AG) sites and shows that Eh is able to splice mRNAs. The spliced Eh cdc2 open reading frame is 291 amino acids (aa) long, encoding an M(r) 33 806 protein. The primary sequence of Eh cdc-2 is most like those of cdc2 homologues Eg1 of Xenopus laevis and CDK2 of man (52% aa identity with each) and codes for (i) the serine (Ser). threonine (Thr), and tyrosine residues phosphorylated in p34cdc2 proteins, (ii) 32 of 33 aa conserved in other Ser/Thr protein kinases, and (iii) the sequence PVTSVRE instead of PSTAIRE found in most p34cdc2 proteins. This is the first cell-division-cycle regulatory protein homologue, as well as the first intron identified from Eh.