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Home > Departments > Genome Biology > Marc MIRANDE : Supramolecular assemblies and translation

Marc MIRANDE : Group Presentation


One of the major objectives of our research program is to provide a comprehensive view, at the molecular level, of the cellular organization in space and in time of the protein synthesis machinery in the eukaryotic cell. We also want to understand the role of components of the translation apparatus in the replication of HIV-1.


Study of aminoacyl-tRNA synthetases, of their catalytic function, of their structural characteristics, and of their organization in space and in time in the protein biosynthesis process, but also of their involvement in non canonical cellular functions, is the recurrent theme of our research project. Several major topics are developed.

Supramolecular assemblies

One of the major objectives of our research program is to provide a comprehensive view of the cellular organization of the protein synthesis machinery in the eukaryotic cell. Several aspects are considered.

The largest supramolecular complex of aaRS described so far is the MARS complex (Multi-Aminoacyl-tRNA Synthetase complex) containing the nine enzymes glutamyl-, prolyl-, isoleucyl-, leucyl-, methionyl-, glutaminyl-, lysyl-, arginyl-, and aspartyl-tRNA synthetases, and the three auxiliary components p43, p38 and p18. The MARS is a key element for cellular homeostasis. It controls the activity of its components in translation, but it also plays a critical regulatory role of the non canonical functions of its components.

A detailed structural and functional study of the macromolecular assemblies that are specific landmarks of the translational machinery in eukaryotes is conducted. A pluridisciplinary approach is undertaken, using the tools of biochemistry, enzymology, molecular, cellular and structural biology. The process of complex assembly is analyzed in vitro but also in cellulo. The cellular functions of eukaryotic synthetases and of the auxiliary components associated with aaRSs are examined in vitro after purification of recombinant proteins, but also by in cellulo methodologies involving overexpression or silencing approaches.

Translation and HIV-1 replication

The primer for reverse transcription of the HIV-1 genome is tRNA3Lys. During assembly of HIV-1 particles, tRNA3Lys is taken up along with LysRS from the host cell, the tRNA binding protein that specifically aminoacylates the different tRNALys isoacceptors. In human, the cytoplasmic and mitochondrial species of LysRS are encoded by a single gene by means of alternative splicing. Using monospecific antibodies raised against synthetic N-terminal peptides that allowed to discriminate between the two enzymes we could establish that mitochondrial LysRS is the only cellular source of viral LysRS. The auxiliary viral protein Vpr alters mitochondrial localization of LysRS in HeLa cells. These results open new routes toward the understanding of the molecular mechanisms involved in the specific packaging of tRNA3Lys into viral particles, and suggest new strategies to block viral life cycle.

Keywords

Traduction, aminoacyl-ARNt synthetases, assemblages supramoléculaires, évolution, réplication virale, HIV-1, tRNA(Lys,3)

Contact


MIRANDE Marc [Senior Researcher - CNRS]
Supramolecular assemblies and Traduction [Leader]
01 69 82 35 05 Gif - Bât 34

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