Cloning and sequence analysis of a novel member of the ATP-binding cassette (ABC) protein gene family from Plasmodium falciparum

Abstract

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 with two ATP-binding folds each containing a Walker A and B consensus motif and an ABC protein signature sequence. The predicted protein is highly hydrophilic and contains numerous phosphorylation consensus sites but does not contain any potential membrane spanning domains. The gene 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 pathway in amino acid starved yeast cells. We have therefore tentatively named the gene Plasmodium falciparum GCN20 homologue (pfgcn20). The pfgcn20 encoded Pfgcn20 protein is also highly homologous to a number of ATP-binding subunits of prokaryotic ABC transporters. We speculate that Pfgcn20 may be an example of a eukaryotic ATP-binding cytosolic subunit of a multipeptide ABC transporter.