Société Française de Biochimie et Biologie Moléculaire

Auriane Monestier - July 2019

Laboratoire de Biochimie, Ecole Polytechnique, CNRS, UMR 7654, Palaiseau Role of aIF1 in Pyrococcus abyssi translation initiation Nucleic Acids Res. 2018,46,11061-11074. doi: 10.1093/nar/gky85Auriane Monestier, Christine Lazennec-Schurdevin, Pierre-Damien Coureux, Yves Mechulam and Emmanuelle Schmitt


Auriane Monestier, 29 years old, is currently a postdoctoral researcher at INRA. After a Master’s Degree in Genomics, Molecular Biology and Microbiology at the University “Paris-Sud”, she obtained a PhD from the Laboratory of biochemistry at Ecole Polytechnique under the supervision of Emmanuelle Schmitt. Her work focused on the formation of the archaeal translation initiation complex. Using toeprinting and fluorescence anisotropy, Auriane Monestier studied the roles of the translation initiation factors in the ribosomal complex. In the selected publication, Auriane Monestier and collaborators described that of the small initiation factor aIF1. The results completed a study conducted by cryo-EM suggesting that a local scanning of the mRNA allows definitive pairing of the initiator tRNA to the start codon.


Auriane Monestier

INRA, team GME institut Micalis

allée de Vilvert.

Bat 442. 

78352 Jouy-en-Josas


In archaeal translation initiation, a preinitiation complex (PIC) made up of aIF1, aIF1A, the ternary complex (TC, e/aIF2-GTP-Met-tRNAiMet) and mRNA bound to the small ribosomal subunit is responsible for start codon selection. Many archaeal mRNAs contain a Shine-Dalgarno (SD) sequence allowing the PIC to be prepositioned in the vicinity of the start codon. Nevertheless, cryo-EM studies have suggested local scanning to definitely establish base pairing of the start codon with the tRNA anticodon. Here, using fluorescence anisotropy, we show that aIF1 and mRNA have synergistic binding to the Pyrococcus abyssi 30S. Stability of 30S:mRNA:aIF1 strongly depends on the SD sequence. Further, toeprinting experiments show that aIF1-containing PICs display a dynamic conformation with the tRNA not firmly accommodated in the P site. AIF1-induced destabilization of the PIC is favorable for proofreading erroneous initiation complexes. After aIF1 departure, the stability of the PIC increases reflecting initiator tRNA fully basepaired to the start codon. Altogether, our data support the idea that some of the main events governing start codon selection in eukaryotes and archaea occur within a common structural and functional core. However, idiosyncratic features in loop 1 sequence involved in 30S:mRNA binding suggest adjustments of e/aIF1 functioning in the two domains.