CLONING AND SEQUENCE-ANALYSIS OF A NOVEL MEMBER OF THE ATP-BINDING CASSETTE (ABC) PROTEIN GENE FAMILY FROM PLASMODIUM-FALCIPARUM

We have employed oligonucleotide primers directed against the Walker A and B ATP-binding consensus motifs in a PCR-approach to clone a novel member of the eukaryotic ABC protein family of genes from Plasmodium falciparum. The novel gene is predicted to encode a 95.5-kDa protein w ith two ATP-binding folds each containing a Walker A and B consensus m otif and an ABC protein signature sequence. The predicted protein is h ighly hydrophilic and contains numerous phosphorylation consensus site s but does not contain any potential membrane spanning domains. The ge ne is present on chromosome 11 and is expressed as a 3.3-kb transcript . The closest homologue with known function to the plasmodial gene is the yeast GCN20 gene which is part of the translation initiation pathw ay in amino acid starved yeast cells. We have therefore tentatively na med the gene Plasmodium falciparum GCN20 homologue (pfgcn20). The pfgc n20 encoded Pfgcn20 protein is also highly homologous to a number of A TP-binding subunits of prokaryotic ABC transporters. We speculate that Pfgcn20 may be an example of a eukaryotic ATP-binding cytosolic subun it of a multipeptide ABC transporter.