Cloning and sequencing of Plasmodium falciparum DNA fragments containing repetitive regions potentially coding for histidine-rich proteins: identification of two overlapping reading frames.

DNA sequences, potentially coding for histidine-rich proteins, were isolated from a P. falciparum genomic library using an oligonucleotide probe consisting of histidine codon repeats. Sequencing revealed that the different DNA fragments contain long repetitive regions very homologous to the probe. One clone was fully sequenced and contains two open reading frames that overlap in the repetitive region but are located on opposite strands. Analysis suggests that both are coding. One frame could code for a small histidine-rich protein, the other for a protein containing many aspartic acid residues. Southern blotting revealed that these sequences are conserved in all three P. falciparum strains studied.