Fluorescently-tagged Human EIF3 for Single-molecule Spectroscopy
Overview
Authors
Affiliations
Human translation initiation relies on the combined activities of numerous ribosome-associated eukaryotic initiation factors (eIFs). The largest factor, eIF3, is an ∼800 kDa multiprotein complex that orchestrates a network of interactions with the small 40S ribosomal subunit, other eIFs, and mRNA, while participating in nearly every step of initiation. How these interactions take place during the time course of translation initiation remains unclear. Here, we describe a method for the expression and affinity purification of a fluorescently-tagged eIF3 from human cells. The tagged eIF3 dodecamer is structurally intact, functions in cell-based assays, and interacts with the HCV IRES mRNA and the 40S-IRES complex in vitro. By tracking the binding of single eIF3 molecules to the HCV IRES RNA with a zero-mode waveguides-based instrument, we show that eIF3 samples both wild-type IRES and an IRES that lacks the eIF3-binding region, and that the high-affinity eIF3-IRES interaction is largely determined by slow dissociation kinetics. The application of single-molecule methods to more complex systems involving eIF3 may unveil dynamics underlying mRNA selection and ribosome loading during human translation initiation.
Bi C, Liu J, Hu X, Yang L, Zhang J Aging (Albany NY). 2023; 15(24):15676-15700.
PMID: 38112620 PMC: 10781468. DOI: 10.18632/aging.205312.
Zero-mode waveguides and nanopore-based sequencing technologies accelerate single-molecule studies.
Iizuka R, Yamazaki H, Uemura S Biophys Physicobiol. 2022; 19:e190032.
PMID: 36349325 PMC: 9592571. DOI: 10.2142/biophysico.bppb-v19.0032.
Lapointe C, Grosely R, Johnson A, Wang J, Fernandez I, Puglisi J Proc Natl Acad Sci U S A. 2021; 118(6).
PMID: 33479166 PMC: 8017934. DOI: 10.1073/pnas.2017715118.
A memory of eS25 loss drives resistance phenotypes.
Johnson A, Flynn R, Lapointe C, Ooi Y, Zhao M, Richards C Nucleic Acids Res. 2020; 48(13):7279-7297.
PMID: 32463448 PMC: 7367175. DOI: 10.1093/nar/gkaa444.
Panthu B, Denolly S, Faivre-Moskalenko C, Ohlmann T, Cosset F, Jalinot P J Biol Chem. 2020; 295(7):1843-1856.
PMID: 31929110 PMC: 7029120. DOI: 10.1074/jbc.RA119.009502.