The alpha-subunit of Leishmania F1 ATP synthase hydrolyzes ATP in presence of tRNA

J Biol Chem. 2006 Jul 14;281(28):18914-7. doi: 10.1074/jbc.C600089200. Epub 2006 May 30.


Import of tRNAs into the mitochondria of the kinetoplastid protozoon Leishmania requires the tRNA-dependent hydrolysis of ATP leading to the generation of membrane potential through the pumping of protons. Subunit RIC1 of the inner membrane RNA import complex is a bi-functional protein that is identical to the alpha-subunit of F1F0 ATP synthase and specifically binds to a subset (Type I) of importable tRNAs. We show that recombinant, purified RIC1 is a Type I tRNA-dependent ATP hydrolase. The activity was insensitive to oligomycin, sensitive to mutations within the import signal of the tRNA, and required the cooperative interaction between the ATP-binding and C-terminal domains of RIC1. The ATPase activity of the intact complex was inhibited by anti-RIC1 antibody, while knockdown of RIC1 in Leishmania tropica resulted in deficiency of the tRNA-dependent ATPase activity of the mitochondrial inner membrane. Moreover, RIC1 knockdown extracts failed to generate a membrane potential across reconstituted proteoliposomes, as shown by a rhodamine 123 uptake assay, but activity was restored by adding back purified RIC1. These observations identify RIC1 as a novel form of the F1 ATP synthase alpha-subunit that acts as the major energy transducer for tRNA import.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / chemistry*
  • Animals
  • Base Sequence
  • Hydrolysis
  • Intracellular Membranes / metabolism
  • Leishmania tropica / enzymology*
  • Liposomes / chemistry
  • Molecular Sequence Data
  • Oligomycins / chemistry
  • Proton-Translocating ATPases / chemistry*
  • Protons
  • RNA / chemistry
  • RNA, Transfer / chemistry*
  • Recombinant Proteins / chemistry
  • Rhodamine 123 / pharmacology


  • Liposomes
  • Oligomycins
  • Protons
  • Recombinant Proteins
  • Rhodamine 123
  • RNA
  • Adenosine Triphosphate
  • RNA, Transfer
  • Proton-Translocating ATPases