Um mecanismo para segregação funcional de códigos genéticos mitocondriais e cistólicos

A mechanism for functional segregation of mitochondrial and cytosolic genetic codes

Yaiza Español a, Daniel Thut b, André Schneider b and Lluís Ribas de Pouplana a,c,1

+ Author Affiliations

aInstitute for Research in Biomedicine (IRB), c/ Baldiri Reixac 15-21 08028, Barcelona, Catalonia, Spain;

bDepartment of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland; and

cCatalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Catalonia, Spain

Edited by Paul R. Schimmel, The Skaggs Institute for Chemical Biology, La Jolla, CA, and approved September 28, 2009 (received for review August 31, 2009)

Abstract

The coexistence of multiple gene translation machineries is a feature of eukaryotic cells and a result of the endosymbiotic events that gave rise to mitochondria, plastids, and other organelles. The conditions required for the integration of these apparatuses within a single cell are not understood, but current evidence indicates that complete ablation of the mitochondrial protein synthesis apparatus and its substitution by its cytosolic equivalent is not possible. Why certain mitochondrial components and not others can be substituted by cytosolic equivalents is not known. In trypanosomatids this situation reaches a limit, because certain aminoacyl-tRNA synthetases are mitochondrial specific despite the fact that all tRNAs in these organisms are shared between cytosol and mitochondria. Here we report that a mitochondria-specific lysyl-tRNA synthetase in Trypanosoma has evolved a mechanism to block the activity of the enzyme during its synthesis and translocation. Only when the enzyme reaches the mitochondria is it activated through the cleavage of a C-terminal structural extension, preventing the possibility of the enzyme being active in the cytosol.

aminoacyl-tRNA synthetases mitochondria tRNA trypanosoma

Footnotes

1To whom correspondence should be addressed. E-mail: lluis.ribas@irbbarcelona.org
Author contributions: L.R.d.P. designed research; Y.E. and D.T. performed research; A.S. and L.R.d.P. analyzed data; and L.R.d.P. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

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