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EMBO J. 2015 Dec 14;34(24):3042-58. doi: 10.15252/embj.201592469. Epub 2015 Nov 24.

Molecular architecture of the ribosome-bound Hepatitis C Virus internal ribosomal entry site RNA.

Author information

1
Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany.
2
Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany UltraStrukturNetzwerk, Max Planck Institute for Molecular Genetics, Berlin, Germany.
3
Structural Biology Programme, CEITEC, Masaryk University, Brno, Czech Republic.
4
Institut für Medizinische Physik und Biophysik, Charité - Universitätsmedizin, Berlin, Germany christian.spahn@charite.de.

Abstract

Internal ribosomal entry sites (IRESs) are structured cis-acting RNAs that drive an alternative, cap-independent translation initiation pathway. They are used by many viruses to hijack the translational machinery of the host cell. IRESs facilitate translation initiation by recruiting and actively manipulating the eukaryotic ribosome using only a subset of canonical initiation factor and IRES transacting factors. Here we present cryo-EM reconstructions of the ribosome 80S- and 40S-bound Hepatitis C Virus (HCV) IRES. The presence of four subpopulations for the 80S•HCV IRES complex reveals dynamic conformational modes of the complex. At a global resolution of 3.9 Å for the most stable complex, a derived atomic model reveals a complex fold of the IRES RNA and molecular details of its interaction with the ribosome. The comparison of obtained structures explains how a modular architecture facilitates mRNA loading and tRNA binding to the P-site. This information provides the structural foundation for understanding the mechanism of HCV IRES RNA-driven translation initiation.

KEYWORDS:

80S ribosome; IRES RNA; cryo‐electron microscopy; internal initiation; translational control

PMID:
26604301
PMCID:
PMC4687786
DOI:
10.15252/embj.201592469
[Indexed for MEDLINE]
Free PMC Article

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