The Archaeal Elongation Factor EF-2 Induces the Release of aIF6 From 50S Ribosomal Subunit

Frontiers in Microbiology

Serena Rosignoli¹  Alessandro Paiardini¹  Giada Lo Gullo²  Anna La Teana³  Alice Romagnoli³  Dario Benelli⁴  Paola Londei⁴  Maria Luisa De Santis⁴ 

[1] Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy;Department of Cellular Biotechnologies and Haematology, Sapienza University of Rome, Rome, Italy;Department of Life and Environmental Science, New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Ancona, Italy;Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy;

关键词: IF6;    EF2;    ribosome;    Sulfolobus solfataricus;    protein synthesis;    SBDS;   

DOI  :  10.3389/fmicb.2021.631297

来源: DOAJ

【 摘 要 】

The translation factor IF6 is a protein of about 25 kDa shared by the Archaea and the Eukarya but absent in Bacteria. It acts as a ribosome anti-association factor that binds to the large subunit preventing the joining to the small subunit. It must be released from the large ribosomal subunit to permit its entry to the translation cycle. In Eukarya, this process occurs by the coordinated action of the GTPase Efl1 and the docking protein SBDS. Archaea do not possess a homolog of the former factor while they have a homolog of SBDS. In the past, we have determined the function and ribosomal localization of the archaeal (Sulfolobus solfataricus) IF6 homolog (aIF6) highlighting its similarity to the eukaryotic counterpart. Here, we analyzed the mechanism of aIF6 release from the large ribosomal subunit. We found that, similarly to the Eukarya, the detachment of aIF6 from the 50S subunit requires a GTPase activity which involves the archaeal elongation factor 2 (aEF-2). However, the release of aIF6 from the 50S subunits does not require the archaeal homolog of SBDS, being on the contrary inhibited by its presence. Molecular modeling, using published structural data of closely related homologous proteins, elucidated the mechanistic interplay between the aIF6, aSBDS, and aEF2 on the ribosome surface. The results suggest that a conformational rearrangement of aEF2, upon GTP hydrolysis, promotes aIF6 ejection. On the other hand, aSBDS and aEF2 share the same binding site, whose occupation by SBDS prevents aEF2 binding, thereby inhibiting aIF6 release.

【 授权许可】

Unknown