title: Nuclear-encoded DnaJ homologue of Plasmodium falciparum interacts with replication ori of the apicoplast genome.
abstract: The apicoplast of Plasmodium falciparum carries a 35 kb circular genome (plDNA) that replicates at the late trophozoite stage of the parasite intraerythocytic cycle. plDNA replication proceeds predominantly via a d-loop/bi-directional ori mechanism with replication ori localized within inverted repeat region. Although replication of the apicoplast genome is a validated drug target, the proteins involved in the replication process are only partially characterized. We analysed DNA-protein interactions at a plDNA replication ori region and report the identification of a nuclear-encoded DnaJ homologue that binds directly to ori elements of the plDNA molecule. PfDnaJ(A) interacted with the minor groove of the DNA double-helix and recognized a 13 bp sequence within the ori. Inhibition of binding with anti-PfDnaJ(A) antibodies confirmed identity of the protein in DNA-binding experiments with organellar protein fractions. The DNA-binding domain of the approximately 69 kDa PfDnaJ(A) lay within the N-terminal 38 kDa region that carries DnaJ signature motifs. In contrast to PfDnaJ(A) in parasite organellar fractions, the recombinant protein interacted with DNA in a sequence non-specific manner. Our results suggest a role for PfDnaJ(A) in replication/repair of the apicoplast genome.
authors.affiliation: Division of Molecular and Structural Biology, Central Drug Research Institute, Lucknow 226001, India.
authors.forename: Ambrish
authors.initials: A
authors.lastname: Kumar
authors.forename: Aiman
authors.initials: A
authors.lastname: Tanveer
authors.forename: Subir
authors.initials: S
authors.lastname: Biswas
authors.forename: Edupuganti V S Raghu
authors.initials: EV
authors.lastname: Ram
authors.forename: Ankit
authors.initials: A
authors.lastname: Gupta
authors.forename: Bijay
authors.initials: B
authors.lastname: Kumar
authors.forename: Saman
authors.initials: S
authors.lastname: Habib
mesh_terms: D001483:Base Sequence; D002467:Cell Nucleus / Q000235:genetics; D004261:DNA Replication; D018503:Genome, Protozoan; D050956:HSP40 Heat-Shock Proteins / Q000378:metabolism*; D010963:Plasmodium falciparum / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018087:Plastids / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism*; D018741:Replication Origin; D053058:Trophozoites / Q000378:metabolism*
chemical_list: D050956:HSP40 Heat-Shock Proteins; D015800:Protozoan Proteins