HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 281, Issue 35, 25270-25277, September 1, 2006

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 281/35/25270    most recent M604126200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Chatterjee, S. Articles by Adhya, S. Search for Related Content PubMed PubMed Citation Articles by Chatterjee, S. Articles by Adhya, S. Social Bookmarking                      What's this?

An RNA-binding Respiratory Component Mediates Import of Type II tRNAs into Leishmania Mitochondria^*

From the Genetic Engineering Laboratory, Indian Institute of Chemical Biology, Calcutta 700032, India

Transport of tRNAs across the inner mitochondrial membrane of the kinetoplastid protozoon Leishmania requires interactions with specific binding proteins (receptors) in a multi-subunit complex. The allosteric model of import regulation proposes cooperative and antagonistic interactions between two or more receptors with binding specificities for distinct tRNA families (types I and II, respectively). To identify the type II receptor, the gene encoding RIC8A, a subunit of the complex, was cloned. The C-terminal region of RIC8A is homologous to subunit 6b of ubiquinol cytochrome c reductase (respiratory complex III), while the N-terminal region has intrinsic affinity for type II, but not for type I, tRNAs. RIC8A is shared by the import complex and complex III, indicating its bi-functionality, but is assembled differently in the two complexes. Knockdown of RIC8A in Leishmania lowered the mitochondrial content of type II tRNAs but raised that of type I tRNAs, with downstream effects on mitochondrial translation and respiration, and cell death. In RIC8A knockdown cells, a subcomplex was formed that interacted with type I tRNA, but the negative regulation by type II tRNA was lost. Mitochondrial extracts from these cells were defective for type II, but not type I, import; import and regulation were restored by purified RIC8A. These results provide evidence for the relevance of allosteric regulation in vivo and indicate that acquisition of new tRNA-binding domains by ancient respiratory components have played a key role in the evolution of mitochondrial tRNA import.

Received for publication, May 1, 2006 , and in revised form, July 6, 2006.

^* This work was supported by Department of Science and Technology Grant SR/SO/BB-28/2003, Council of Scientific and Industrial Research (CSIR) Project SMM 003, CSIR fellowships (to S. G., G. D., B. M., S. M., and P. H.), and a University Grants Commission fellowship (to S. C.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental Table S1 and supplemental Figs. S1 and S2.

¹ To whom correspondence should be addressed: Genetic Engineering Laboratory, Indian Institute of Chemical Biology, 4 Raja S.C. Mullick Road, Calcutta 700032, India. Tel.: 91-33-2473-3491 (ext. 136); Fax: 91-33-2473-5197; E-mail: sadhya{at}iicb.res.in.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				A. Zikova, A. K. Panigrahi, A. D. Uboldi, R. A. Dalley, E. Handman, and K. Stuart Structural and Functional Association of Trypanosoma brucei MIX Protein with Cytochrome c Oxidase Complex Eukaryot. Cell, November 1, 2008; 7(11): 1994 - 2003. [Abstract] [Full Text] [PDF]

				P. Home, S. Mukherjee, and S. Adhya A mosaic of RNA binding and protein interaction motifs in a bifunctional mitochondrial tRNA import factor from Leishmania tropica Nucleic Acids Res., October 1, 2008; 36(17): 5552 - 5561. [Abstract] [Full Text] [PDF]

				S. Basu, S. Mukherjee, and S. Adhya Proton-guided movements of tRNA within the Leishmania mitochondrial RNA import complex Nucleic Acids Res., March 1, 2008; 36(5): 1599 - 1609. [Abstract] [Full Text] [PDF]

				T. Salinas, A.-M. Duchene, L. Delage, S. Nilsson, E. Glaser, M. Zaepfel, and L. Marechal-Drouard The voltage-dependent anion channel, a major component of the tRNA import machinery in plant mitochondria PNAS, November 28, 2006; 103(48): 18362 - 18367. [Abstract] [Full Text] [PDF]