Identification of an MCM4 homologue expressed specifically in the sexual stage of Plasmodium falciparum

Mini-chromosome maintenance (MCM) proteins play an essential role in DNA re plication initiation. We have isolated a novel gene encoding an MCM-like pr otein from the human malaria parasite Plasmodium falciparum using the vecto rette technique. The gene has no introns and comprises an open reading fram e encoding 1005 amino acid residues with a predicted Mr of 115 kDa. The enc oded protein, termed PfMCM4, contains all conserved sequences in the MCM fa mily and displays the highest homology to the Cdc54 (MCM4) of Saccharomyces cerevisiae. However, PfMCM4 possesses five unique amino acid inserts with sizes ranging from seven to 75 residues. Southern blotting of genomic DNA d igests and chromosomal separations showed that the pfmcm4 gene is present a s a single copy per haploid genome and is located on chromosome 13. A 4000- nucleotide transcript of this gene is expressed specifically in the sexual erythrocytic stage. indicating that PfMCM4 may be involved in gametogenesis in which DNA is quickly replicated. (C) 2001 Australian Society for Parasi tology Inc. Published by Elsevier Science Ltd. All rights reserved.