2Centre National de la Recherche Scientifique (CNRS) UMR 7104, 67404 Illkirch, France
3Institut National de la Santé et de la Recherche Médicale (INSERM) U964, 67404 Illkirch, France
4Université de Strasbourg, 67081 Strasbourg, France
Received May 20, 2021; Revised May 20, 2021; Accepted June 6, 2021
“Would it be possible to analyze molecular mechanisms and structural organisation of polyribosome assemblies using cryo electron tomography?” – we asked through a longstanding collaboration between my research group and that of Alexander S. Spirin. Indeed, it was: we found that double-row polyribosomes can have both circular and linear arrangements of their mRNA [Afonina, Z. A., et al. (2013) Biochemistry (Moscow)], we figured out how eukaryotic ribosomes assemble on an mRNA to form supramolecular left-handed helices [Myasnikov, A. G., et al. (2014) Nat. Commun.], that the circularization of polyribosomes is poly-A and cap-independent [Afonina, Z. A., et al. (2014) Nucleic Acids Res.], and that intermediary polyribosomes with open structures exist after a transition from a juvenile phase to strongly translating polysomes of medium size [Afonina, Z. A., et al. (2015) Nucleic Acids Res.] until they form densely packed helical structures with reduced activity. Our joint fruitful exchanges, hence, led to major advances in the field, which are reviewed here from a personal and historical perspective in memory of Alexander S. Spirin.
KEY WORDS: polyribosomes, polysomes, eukaryotic ribosomes, cryo electron microscopy, cryo electron tomography