A bifunctional tRNA import receptor from Leishmania mitochondria

Goswami, Srikanta and Dhar, Gunjan and Mukherjee, Saikat and Mahata, Bidesh and Chatterjee, Saibal and Home, Pratik and Adhya, Samit (2006) A bifunctional tRNA import receptor from Leishmania mitochondria. Proceedings of the National Academy of Sciences of the United States of America (PNAS) ISSN 1091-6490, 103 (22). pp. 8354-8359.

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    Abstract

    In kinetoplastid protozoa, import of cytosolic tRNAs into mitochondria occurs through tRNAs interacting with membrane-bound proteins, the identities of which are unknown. The inner membrane RNA import complex of Leishmania tropica contains multiple proteins and is active for import in vitro. RIC1, the largest subunit of this complex, is structurally homologous to the conserved � subunit of F1 ATP synthase. The RIC1 gene complemented an atpA mutation in Escherichia coli. Antisense-mediated knockdown of RIC1�F1� in Leishmania resulted in depletion of several mitochondrial tRNAs belonging to distinct subsets (types I and II) that interact cooperatively or antagonistically within the import complex. The knockdown-induced defect in import of type I tRNAs was rectified in a reconstituted system by purified RIC1�F1� alone, but recovery of type II tRNA import additionally required a type I tRNA. RIC1�F1� formed stable complexes with type I, but not type II, tRNAs through the cooperation of its nucleotide binding and C-terminal domains. Thus, RIC1�F1� is a type I tRNA import receptor. As expected of a bifunctional protein, RIC1�F1� is shared by both the import complex and by respiratory complex V. Alternative use of ancient respiratory proteins may have been an important step in the evolution of tRNA import.

    Item Type: Article
    URI: http://www.eprints.iicb.res.in/id/eprint/480
    Subjects: Molecular & Human Genetics
    Divisions: Indian Institute of Chemical Biology
    Depositing User: Ms Sutapa Ganguly
    Date Deposited: 02 Nov 2011 12:06
    Last Modified: 03 Feb 2012 12:16
    Official URL: http://dx.doi.org/10.1073�pnas.0510869103
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