eIF3 (eukaryotic initiation factor 3) is the largest and most complex eukaryotic mRNA translation factor in terms of the number of protein components or subunits. In mammals, eIF3 is composed of 13 different polypeptide subunits, of which five, i.e. a, b, c, g and i, are conserved and essential in vivo from yeasts to mammals. In the present study, we show that the eukaryotic cytosolic chaperonin CCT [chaperonin containing TCP-1 (tailless complex polypeptide 1)] binds to newly synthesized eIF3b and promotes the correct folding of eIF3h and eIF3i. Interestingly, overexpression of these last two subunits is associated with enhanced translation of specific mRNAs over and above the general enhancement of global translation. In agreement with this, our data show that, as CCT is required for the correct folding of eIF3h and eIF3i subunits, it indirectly influences gene expression with eIF3i overexpression enhancing both cap- and IRES (internal ribosome entry segment)-dependent translation initiation, whereas eIF3h overexpression selectively increases IRES-dependent translation initiation. Importantly, these studies demonstrate the requirement of the chaperonin machinery for the correct folding of essential components of the translational machinery and provide further evidence of the close interplay between the cell environment, cell signalling, cell proliferation, the chaperone machinery and translational apparatus.
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Research Article|
February 14 2014
The chaperonin CCT interacts with and mediates the correct folding and activity of three subunits of translation initiation factor eIF3: b, i and h
Anne Roobol;
Anne Roobol
*Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, U.K.
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Jo Roobol;
Jo Roobol
*Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, U.K.
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Martin J. Carden;
Martin J. Carden
*Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, U.K.
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Matthew E. Smith;
Matthew E. Smith
*Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, U.K.
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John W. B. Hershey;
John W. B. Hershey
†Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA 95616, U.S.A.
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Amandine Bastide;
Amandine Bastide
‡MRC Toxicology Unit, Hodgkin Building, P.O. Box 138, University of Leicester, Lancaster Road, Leicester LE1 9HN, U.K.
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John R. P. Knight;
John R. P. Knight
‡MRC Toxicology Unit, Hodgkin Building, P.O. Box 138, University of Leicester, Lancaster Road, Leicester LE1 9HN, U.K.
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Anne E. Willis;
Anne E. Willis
1
‡MRC Toxicology Unit, Hodgkin Building, P.O. Box 138, University of Leicester, Lancaster Road, Leicester LE1 9HN, U.K.
1Correspondence may be addressed to either of these authors (email aew5@le.ac.uk or c.m.smales@kent.ac.uk).
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C. Mark Smales
C. Mark Smales
1
*Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, U.K.
1Correspondence may be addressed to either of these authors (email aew5@le.ac.uk or c.m.smales@kent.ac.uk).
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Publisher: Portland Press Ltd
Received:
July 25 2013
Revision Received:
December 03 2013
Accepted:
December 10 2013
Accepted Manuscript online:
December 10 2013
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2014 Biochemical Society
2014
Biochem J (2014) 458 (2): 213–224.
Article history
Received:
July 25 2013
Revision Received:
December 03 2013
Accepted:
December 10 2013
Accepted Manuscript online:
December 10 2013
Citation
Anne Roobol, Jo Roobol, Martin J. Carden, Matthew E. Smith, John W. B. Hershey, Amandine Bastide, John R. P. Knight, Anne E. Willis, C. Mark Smales; The chaperonin CCT interacts with and mediates the correct folding and activity of three subunits of translation initiation factor eIF3: b, i and h. Biochem J 1 March 2014; 458 (2): 213–224. doi: https://doi.org/10.1042/BJ20130979
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