MALARIA PARASITES CONTAIN 2 IDENTICAL COPIES OF AN ELONGATION-FACTOR-1 ALPHA-GENE

Elongation factor 1alpha (EF-1 alpha) is an abundant protein in eukary otic cells, involved chiefly in translation of mRNA on the ribosomes, and is frequently encoded by more than one gene. Here we show the pres ence of two identical copies of the EF-1 alpha gene in the genome of t hree malaria parasites, Plasmodium knowlesi, P. berghei and P. falcipa rum. They are organized in a head-to-head orientation and both genes a re expressed in a stage specific manner at a high level, indicating th at the small intergenic region contains either two strong promoters or a single bidirectional one. Both genes are expressed at the same time during erythrocytic development of the parasite. This expression patt ern and the 100% similarity of the two genes excludes the possibility that the duplicated genes developed in accordance to the different typ es of ribosomes in Plasmodium. It is more likely that the duplication reflects a gene dosage effect. Comparison of codon usage in the Cdc2-r elated kinase genes (CRK2) of Plasmodium, which are expressed at a ver y low level, with the EF-1 alpha genes indicates the existence of a co don bias for highly expressed genes, as has been shown in other organi sms. (C) 1998 Elsevier Science B.V. All rights reserved.