title: Cloning, sequence determination, and regulation of the ribonucleotide reductase subunits from Plasmodium falciparum: a target for antimalarial therapy.
abstract: Malaria remains a leading cause of morbidity and mortality worldwide, accounting for more than one million deaths annually. We have focused on the reduction of ribonucleotides to 2'-deoxyribonucleotides, catalyzed by ribonucleotide reductase, which represents the rate-determining step in DNA replication as a target for antimalarial agents. We report the full-length DNA sequence corresponding to the large (PfR1) and small (PfR2) subunits of Plasmodium falciparum ribonucleotide reductase. The small subunit (PfR2) contains the major catalytic motif consisting of a tyrosyl radical and a dinuclear Fe site. Whereas PfR2 shares 59% amino acid identity with human R2, a striking sequence divergence between human R2 and PfR2 at the C terminus may provide a selective target for inhibition of the malarial enzyme. A synthetic oligopeptide corresponding to the C-terminal 7 residues of PfR2 inhibits mammalian ribonucleotide reductase at concentrations approximately 10-fold higher than that predicted to inhibit malarial R2. The gene encoding the large subunit (PfR1) contains a single intron. The cysteines thought to be involved in the reduction mechanism are conserved. In contrast to mammalian ribonucleotide reductase, the genes for PfR1 and PfR2 are located on the same chromosome and the accumulation of mRNAs for the two subunits follow different temporal patterns during the cell cycle.
authors.affiliation: Department of Medicine, University of Pennsylvania, Philadelphia 19104.
authors.forename: H
authors.initials: H
authors.lastname: Rubin
authors.forename: J S
authors.initials: JS
authors.lastname: Salem
authors.forename: L S
authors.initials: LS
authors.lastname: Li
authors.forename: F D
authors.initials: FD
authors.lastname: Yang
authors.forename: S
authors.initials: S
authors.lastname: Mama
authors.forename: Z M
authors.initials: ZM
authors.lastname: Wang
authors.forename: A
authors.initials: A
authors.lastname: Fisher
authors.forename: C S
authors.initials: CS
authors.lastname: Hamann
authors.forename: B S
authors.initials: BS
authors.lastname: Cooperman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000962:Antimalarials; D001483:Base Sequence; D001665:Binding Sites; D002453:Cell Cycle; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D017125:Genes, Protozoan; D006801:Humans; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000201:enzymology / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D012264:Ribonucleotide Reductases / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D000962:Antimalarials; D017931:DNA Primers; D012333:RNA, Messenger; D007501:Iron; D012264:Ribonucleotide Reductases