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Molecular landscape of the ribosome pre-initiation complex during mRNA scanning: structural role for eIF3c and its control by eIF5

Obayashi, Eiji
Luna, Rafael E.
Nagata, Takashi
Martin-Marcos, Pilar
Hiraishi, Hiroyuki
Singh, Chingakham Ranjit
Erzberger, Jan Peter
Zhang, Fan
Arthanari, Haribabu
Morris, Jacob
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Abstract
During eukaryotic translation initiation, eIF3 binds the solvent-accessible side of the 40S ribosome and recruits the gate-keeper protein eIF1 and eIF5 to the decoding center. This is largely mediated by the N-terminal domain (NTD) of eIF3c, which can be divided into three parts: 3c0, 3c1 and 3c2. The N-terminal part, 3c0, binds eIF5 strongly, but only weakly to the ribosome-binding surface of eIF1, whereas 3c1 and 3c2 form a stoichiometric complex with eIF1. 3c1 contacts eIF1 through Arg-53 and Leu-96, while 3c2 faces 40S protein uS15/S13, to anchor eIF1 to the scanning pre-initiation complex (PIC). We propose that the 3c0:eIF1 interaction diminishes eIF1 binding to the 40S, whereas 3c0:eIF5 interaction stabilizes the scanning PIC by precluding this inhibitory interaction. Upon start codon recognition, interactions involving eIF5, and ultimately 3c0:eIF1 association facilitate eIF1 release. Our results reveal intricate molecular interactions within the PIC, programmed for rapid scanning-arrest at the start codon.
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2017-04-06
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Elsevier
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Obayashi, E., Luna, R. E., Nagata, T., Martin-Marcos, P., Hiraishi, H., Singh, C. R., … Asano, K. (2017). Molecular landscape of the ribosome pre-initiation complex during mRNA scanning: structural role for eIF3c and its control by eIF5. Cell Reports, 18(11), 2651–2663. http://doi.org/10.1016/j.celrep.2017.02.052
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