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EMBO Rep. 2007 Jun;8(6):589-95. Epub 2007 May 18.

Necessary and sufficient factors for the import of transfer RNA into the kinetoplast mitochondrion.

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Genetic Engineering Laboratory, Indian Institute of Chemical Biology, 4 Raja S.C. Mullick Road, Calcutta 700032, India.

Erratum in

  • EMBO Rep. 2011 Jun;12(6):607.
  • EMBO Rep. 2009 Jan;10(1):101.


The mechanism of active transport of transfer RNA (tRNA) across membranes is largely unknown. Factors mediating the import of tRNA into the kinetoplast mitochondrion of the protozoon Leishmania tropica are organized into a multiprotein RNA import complex (RIC) at the inner membrane. Here, we present the complete characterization of the identities and functions of the subunits of this complex. The complex contains three mitochondrion- and eight nuclear-encoded subunits; six of the latter are necessary and sufficient for import. Antisense-mediated knockdown of essential subunits resulted in the depletion of mitochondrial tRNAs and inhibition of organellar translation. Functional complexes were reconstituted with recombinant subunits expressed in Escherichia coli. Several essential RIC subunits are identical to specific subunits of respiratory complexes. These findings provide new information on the evolution of tRNA import and the foundation for detailed structural and mechanistic studies.

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