title: Interaction of apicoplast-encoded elongation factor (EF) EF-Tu with nuclear-encoded EF-Ts mediates translation in the Plasmodiumfalciparum plastid.
abstract: Protein translation in the plastid (apicoplast) of Plasmodium spp. is of immense interest as a target for potential anti-malarial drugs. However, the molecular data on apicoplast translation needed for optimisation and development of novel inhibitors is lacking. We report characterisation of two key translation elongation factors in Plasmodium falciparum, apicoplast-encoded elongation factor PfEF-Tu and nuclear-encoded PfEF-Ts. Recombinant PfEF-Tu hydrolysed GTP and interacted with its presumed nuclear-encoded partner PfEF-Ts. The EF-Tu inhibitor kirromycin affected PfEF-Tu activity in vitro, indicating that apicoplast EF-Tu is indeed the target of this drug. The predicted PfEF-Ts leader sequence targeted GFP to the apicoplast, confirming that PfEF-Ts functions in this organelle. Recombinant PfEF-Ts mediated nucleotide exchange on PfEF-Tu and homology modeling of the PfEF-Tu:PfEF-Ts complex revealed PfEF-Ts-induced structural alterations that would expedite GDP release from PfEF-Tu. Our results establish functional interaction between two apicoplast translation factors encoded by genes residing in different cellular compartments and highlight the significance of their sequence/structural differences from bacterial elongation factors in relation to inhibitor activity. These data provide an experimental system to study the effects of novel inhibitors targeting PfEF-Tu and PfEF-Tu.PfEF-Ts interaction. Our finding that apicoplast EF-Tu possesses chaperone-related disulphide reductase activity also provides a rationale for retention of the tufA gene on the plastid genome.
authors.affiliation: Division of Molecular and Structural Biology, Central Drug Research Institute, PO Box 173, Chattar Manzil, Mahatma Gandhi Marg, Lucknow 226001, India.
authors.forename: Subir
authors.initials: S
authors.lastname: Biswas
authors.forename: Erin E
authors.initials: EE
authors.lastname: Lim
authors.forename: Ankit
authors.initials: A
authors.lastname: Gupta
authors.forename: Uzma
authors.initials: U
authors.lastname: Saqib
authors.forename: Snober S
authors.initials: SS
authors.lastname: Mir
authors.forename: Mohammad Imran
authors.initials: MI
authors.lastname: Siddiqi
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Ralph
authors.forename: Saman
authors.initials: S
authors.lastname: Habib
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D010444:Peptide Elongation Factor Tu / Q000737:chemistry / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D010445:Peptide Elongation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010963:Plasmodium falciparum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D018087:Plastids / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D011728:Pyridones / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D010445:Peptide Elongation Factors; D015800:Protozoan Proteins; D011728:Pyridones; C036506:elongation factor T; D010444:Peptide Elongation Factor Tu; C008536:mocimycin