Cellular mRNA recruits the ribosome via eIF3-PABP bridge to initiate internal translation

Nehal Thakor; M Duane Smith; Luc Roberts; Mame Daro Faye; Harshil Patel; Hans-Joachim Wieden; Jamie H D Cate; Martin Holcik

doi:10.1080/15476286.2015.1137419

Cellular mRNA recruits the ribosome via eIF3-PABP bridge to initiate internal translation

RNA Biol. 2017 May 4;14(5):553-567. doi: 10.1080/15476286.2015.1137419. Epub 2016 Feb 1.

Authors

Nehal Thakor^{1

2}, M Duane Smith³, Luc Roberts², Mame Daro Faye¹, Harshil Patel², Hans-Joachim Wieden², Jamie H D Cate³, Martin Holcik^{1

4}

Affiliations

¹ a Apoptosis Research Center , Children's Hospital of Eastern Ontario Research Institute , Ottawa , Ontario , Canada.
² c Department of Chemistry and Biochemistry , Alberta RNA Research and Training Institute, University of Lethbridge , Lethbridge , AB , Canada.
³ d Department of Molecular and Cell Biology , University of California , Berkeley , CA , USA.
⁴ b Department of Pediatrics , University of Ottawa , Ottawa , Ontario , Canada.

Abstract

IRES-mediated translation of key cell fate regulating genes has been implicated in tumorigenesis. Concerted action of canonical eukaryotic initiation factors and IRES transacting factors (ITAFs) was shown to regulate cellular IRES mediated translation; however, the precise molecular mechanism of ribosome recruitment to cellular IRESes remains unclear. Here we show that the X-linked inhibitor of apoptosis (XIAP) IRES operates in an evolutionary conserved viral like mode and the structural integrity, particularly in the vicinity of AUG, is critical for ribosome recruitment. The binding of eIF3 together with PABP potentiates ribosome recruitment to the IRES. Our data support the model in which eIF3 binds directly to the XIAP IRES RNA in a structure-dependent manner and acts as a scaffold for IRES RNA, PABP and the 40S ribosome.

Keywords: Cellular IRES; NMIA-SHAPE; PABP; RNA structure; XIAP; eIF3; toeprinting assay.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Apoptosis
Codon, Initiator / metabolism
Eukaryotic Initiation Factor-3 / metabolism*
Eukaryotic Initiation Factors / metabolism
HeLa Cells
Humans
Internal Ribosome Entry Sites*
Poly(A)-Binding Proteins / metabolism*
Protein Biosynthesis / physiology*
RNA, Messenger / genetics
RNA, Messenger / metabolism*
Ribosome Subunits, Small, Eukaryotic / genetics
Ribosome Subunits, Small, Eukaryotic / metabolism
Ribosomes / metabolism*
X-Linked Inhibitor of Apoptosis Protein / genetics
X-Linked Inhibitor of Apoptosis Protein / metabolism*

Substances

Codon, Initiator
Eukaryotic Initiation Factor-3
Eukaryotic Initiation Factors
Internal Ribosome Entry Sites
Poly(A)-Binding Proteins
RNA, Messenger
X-Linked Inhibitor of Apoptosis Protein
XIAP protein, human

Grants and funding

MOP 89737/CIHR/Canada