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The eukaryotic initiation factor eIF4H facilitates loop-binding, repetitive RNA unwinding by the eIF4A DEAD-box helicase

Eukaryotic translation initiation is a highly regulated process in protein synthesis. The principal translation initiation factor eIF4AI displays helicase activity, unwinding secondary structures in the mRNAs 5′-UTR. Single molecule fluorescence resonance energy transfer (sm-FRET) is applied here to...

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Autores principales: Sun, Yingjie, Atas, Evrim, Lindqvist, Lisa, Sonenberg, Nahum, Pelletier, Jerry, Meller, Amit
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3401463/
https://www.ncbi.nlm.nih.gov/pubmed/22457067
http://dx.doi.org/10.1093/nar/gks278
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author Sun, Yingjie
Atas, Evrim
Lindqvist, Lisa
Sonenberg, Nahum
Pelletier, Jerry
Meller, Amit
author_facet Sun, Yingjie
Atas, Evrim
Lindqvist, Lisa
Sonenberg, Nahum
Pelletier, Jerry
Meller, Amit
author_sort Sun, Yingjie
collection PubMed
description Eukaryotic translation initiation is a highly regulated process in protein synthesis. The principal translation initiation factor eIF4AI displays helicase activity, unwinding secondary structures in the mRNAs 5′-UTR. Single molecule fluorescence resonance energy transfer (sm-FRET) is applied here to directly observe and quantify the helicase activity of eIF4AI in the presence of the ancillary RNA-binding factor eIF4H. Results show that eIF4H can significantly enhance the helicase activity of eIF4AI by strongly binding both to loop structures within the RNA transcript as well as to eIF4AI. In the presence of ATP, the eIF4AI/eIF4H complex exhibits persistent rapid and repetitive cycles of unwinding and re-annealing. ATP titration assays suggest that this process consumes a single ATP molecule per cycle. In contrast, helicase unwinding activity does not occur in the presence of the non-hydrolysable analog ATP-γS. Based on our sm-FRET results, we propose an unwinding mechanism where eIF4AI/eIF4H can bind directly to loop structures to destabilize duplexes. Since eIF4AI is the prototypical example of a DEA(D/H)-box RNA helicase, it is highly likely that this unwinding mechanism is applicable to a myriad of DEAD-box helicases employed in RNA metabolism.
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spelling pubmed-34014632012-07-23 The eukaryotic initiation factor eIF4H facilitates loop-binding, repetitive RNA unwinding by the eIF4A DEAD-box helicase Sun, Yingjie Atas, Evrim Lindqvist, Lisa Sonenberg, Nahum Pelletier, Jerry Meller, Amit Nucleic Acids Res Nucleic Acid Enzymes Eukaryotic translation initiation is a highly regulated process in protein synthesis. The principal translation initiation factor eIF4AI displays helicase activity, unwinding secondary structures in the mRNAs 5′-UTR. Single molecule fluorescence resonance energy transfer (sm-FRET) is applied here to directly observe and quantify the helicase activity of eIF4AI in the presence of the ancillary RNA-binding factor eIF4H. Results show that eIF4H can significantly enhance the helicase activity of eIF4AI by strongly binding both to loop structures within the RNA transcript as well as to eIF4AI. In the presence of ATP, the eIF4AI/eIF4H complex exhibits persistent rapid and repetitive cycles of unwinding and re-annealing. ATP titration assays suggest that this process consumes a single ATP molecule per cycle. In contrast, helicase unwinding activity does not occur in the presence of the non-hydrolysable analog ATP-γS. Based on our sm-FRET results, we propose an unwinding mechanism where eIF4AI/eIF4H can bind directly to loop structures to destabilize duplexes. Since eIF4AI is the prototypical example of a DEA(D/H)-box RNA helicase, it is highly likely that this unwinding mechanism is applicable to a myriad of DEAD-box helicases employed in RNA metabolism. Oxford University Press 2012-07 2012-03-28 /pmc/articles/PMC3401463/ /pubmed/22457067 http://dx.doi.org/10.1093/nar/gks278 Text en © The Author(s) 2012. Published by Oxford University Press. http://creativecommons.org/licenses/by-nc/3.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Nucleic Acid Enzymes
Sun, Yingjie
Atas, Evrim
Lindqvist, Lisa
Sonenberg, Nahum
Pelletier, Jerry
Meller, Amit
The eukaryotic initiation factor eIF4H facilitates loop-binding, repetitive RNA unwinding by the eIF4A DEAD-box helicase
title The eukaryotic initiation factor eIF4H facilitates loop-binding, repetitive RNA unwinding by the eIF4A DEAD-box helicase
title_full The eukaryotic initiation factor eIF4H facilitates loop-binding, repetitive RNA unwinding by the eIF4A DEAD-box helicase
title_fullStr The eukaryotic initiation factor eIF4H facilitates loop-binding, repetitive RNA unwinding by the eIF4A DEAD-box helicase
title_full_unstemmed The eukaryotic initiation factor eIF4H facilitates loop-binding, repetitive RNA unwinding by the eIF4A DEAD-box helicase
title_short The eukaryotic initiation factor eIF4H facilitates loop-binding, repetitive RNA unwinding by the eIF4A DEAD-box helicase
title_sort eukaryotic initiation factor eif4h facilitates loop-binding, repetitive rna unwinding by the eif4a dead-box helicase
topic Nucleic Acid Enzymes
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3401463/
https://www.ncbi.nlm.nih.gov/pubmed/22457067
http://dx.doi.org/10.1093/nar/gks278
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