Bijay Kumar

Publications (3)13.41 Total impact

• Article: Interaction between sulphur mobilisation proteins SufB and SufC: evidence for an iron-sulphur cluster biogenesis pathway in the apicoplast of Plasmodium falciparum.

  Bijay Kumar, Sushma Chaubey, Priyanka Shah, Aiman Tanveer, Manish Charan, Mohammad Imran Siddiqi, Saman Habib
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  ABSTRACT: The plastid of Plasmodium falciparum, the apicoplast, performs metabolic functions essential to the parasite. Various reactions in the plastid require the assembly of [Fe-S] prosthetic groups on participating proteins as well as the reductant activity of ferredoxin that is converted from its apo-form by the assembly of [Fe-S] clusters inside the apicoplast. The [Fe-S] assembly pathway involving sulphur mobilising Suf proteins has been predicted to function in the apicoplast with one component (PfSufB) encoded by the plastid genome itself. We demonstrate the ATPase activity of recombinant P. falciparum nuclear-encoded SufC and its localisation in the apicoplast. Further, an internal region of apicoplast SufB was used to detect PfSufB-PfSufC interaction in vitro; co-elution of SufB from parasite lysate with recombinant PfSufC on an affinity column also indicated an interaction of the two proteins. As a departure from bacterial SufB and similar to reported plant plastid SufB, apicoplast SufB exhibited ATPase activity, suggesting the evolution of specialised functions in the plastid counterparts. Our results provide experimental evidence for an active Suf pathway in the Plasmodium apicoplast.
  International journal for parasitology 06/2011; 41(9):991-9. · 3.39 Impact Factor
• Article: Nuclear-encoded DnaJ homologue of Plasmodium falciparum interacts with replication ori of the apicoplast genome.

  Ambrish Kumar, Aiman Tanveer, Subir Biswas, Edupuganti V S Raghu Ram, Ankit Gupta, Bijay Kumar, Saman Habib
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  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.
  Molecular Microbiology 02/2010; 75(4):942-56. · 5.01 Impact Factor
• Article: Nuclear-encoded DnaJ homolog of Plasmodium falciparum interacts with replication ori of the apicoplast genome.

  Ambrish Kumar, Aiman Tanveer, Subir Biswas, Evs Raghu Ram, Ankit Gupta, Bijay Kumar, Saman Habib
  [show abstract] [hide abstract]
  ABSTRACT: Summary 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 analyzed DNA-protein interactions at a plDNA replication ori region and report the identification of a nuclear-encoded DnaJ homolog 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.
  Molecular Microbiology 01/2010; · 5.01 Impact Factor