In recent years, our thinking of how the initiation of protein synthesis occurs has changed dramatically. Initiation was thought to involve only events occurring at or near the 5′-cap structure, which serves as the binding site for the cap-binding complex, a group of translation initiation factors (eIFs) that facilitate the binding of the 40 S ribosomal subunit to an mRNA. Because the poly(A)-binding protein (PABP) binds the poly(A) tail present at the 3′-terminus of an mRNA, it was long thought to play no role in translation initiation. In this review, I present evidence from my laboratory that has contributed to the paradigm shift in how we think of mRNAs during translation. The depiction of mRNAs as straight molecules in which the poly(A) tail is far from events occurring at the 5′-end has now been replaced by the concept of a circular mRNA where the interaction between PABP and the cap-binding complex bridges the termini of an mRNA and promotes translation initiation. The research from my laboratory supports the new paradigm that translation of most mRNAs requires a functional and physical interaction between the termini of an mRNA. 1. Introduction Our understanding of how mRNAs are translated into proteins has undergone a paradigm shift in recent years. Prior to this shift, a translating mRNA undergoing translation was thought of as a straight molecule and protein synthesis was considered a linear process that encompassed three phases. In this prior view, the first phase, that is, translation initiation, begins with events that only involve the 5′-end of an mRNA in which the subunits of a ribosome are recruited and assembled at the initiation codon and conclude with the synthesis of the first peptide bond (Figure 1). This is followed by the elongation phase, that is, the ribosome-catalyzed decoding of the open reading frame into protein and finally the recognition of the stop codon and release of the nascent peptide from the ribosome. In this paper, I will illustrate how our understanding of how mRNAs undergoing translation in eukaryotes fundamentally changed from a view in which translation initiation is orchestrated by events only involving the 5′-end of an mRNA to one in which the mRNA is circularized by functional and physical interactions between the termini of an mRNA. As my research involves translation in plants, findings from this kingdom this will be emphasized. However, the similarities and differences in the interactions of the machinery involved in ribosome recruitment in plants and those of other eukaryotes will be also be discussed.
References
[1]
J. Shine and L. Dalgarno, “The 3′ terminal sequence of Escherichia coli 16S ribosomal RNA: complementarity to nonsense triplets and ribosome binding sites,” Proceedings of the National Academy of Sciences of the United States of America, vol. 71, no. 4, pp. 1342–1346, 1974.
[2]
M. Kozak, “At least six nucleotides preceding the AUG initiator codon enhance translation in mammalian cells,” Journal of Molecular Biology, vol. 196, no. 4, pp. 947–950, 1987.
[3]
T. Preiss and M. W. Hentze, “Starting the protein synthesis machine: eukaryotic translation initiation,” BioEssays, vol. 25, no. 12, pp. 1201–1211, 2003.
[4]
L. D. Kapp and J. R. Lorsch, “The molecular mechanics of eukaryotic translation,” Annual Review of Biochemistry, vol. 73, pp. 657–704, 2004.
[5]
T. V. Pestova, J. R. Lorsch, and C. U. T. Hellen, “The mechanism of translation initiation in eukaryotes,” in Translational Control in Biology and Medicine, M. B. Mathews, N. Sonenberg, and J. W. B. Hershey, Eds., pp. 87–128, Cold Spring Harbor Laboratory Press, 2007.
[6]
D. R. Gallie, “Protein-protein interactions required during translation,” Plant Molecular Biology, vol. 50, no. 6, pp. 949–970, 2002.
[7]
B. K. Ray, T. G. Lawson, J. C. Kramer et al., “ATP-dependent unwinding of messenger RNA structure by eukaryotic initiation factors,” The Journal of Biological Chemistry, vol. 260, no. 12, pp. 7651–7658, 1985.
[8]
R. D. Abramson, T. E. Dever, T. G. Lawson, B. K. Ray, R. E. Thach, and W. C. Merrick, “The ATP-dependent interaction of eukaryotic initiation factors with mRNA.,” Journal of Biological Chemistry, vol. 262, no. 8, pp. 3826–3832, 1987.
[9]
T. G. Lawson, K. A. Lee, M. M. Maimone et al., “Dissociation of double-stranded polynucleotide helical structures by eukaryotic initiation factors, as revealed by a novel assay,” Biochemistry, vol. 28, no. 11, pp. 4729–4734, 1989.
[10]
S. C. Milburn, J. W. B. Hershey, M. V. Davies, K. Kelleher, and R. J. Kaufman, “Cloning and expression of eukaryotic initiation factor 4B cDNA: sequence determination identifies a common RNA recognition motif,” EMBO Journal, vol. 9, no. 9, pp. 2783–2790, 1990.
[11]
F. Rozen, I. Edery, K. Meerovitch, T. E. Dever, W. C. Merrick, and N. Sonenberg, “Bidirectional RNA helicase activity of eucaryotic translation initiation factors 4A and 4F,” Molecular and Cellular Biology, vol. 10, no. 3, pp. 1134–1144, 1990.
[12]
M. Jaramillo, T. E. Dever, W. C. Merrick, and N. Sonenberg, “RNA unwinding in translation: assembly of helicase complex intermediates comprising eukaryotic initiation factors eIF-4F and eIF-4B,” Molecular and Cellular Biology, vol. 11, no. 12, pp. 5992–5997, 1991.
[13]
M. Altmann, P. P. Muller, B. Wittmer, F. Ruchti, S. Lanker, and H. Trachsel, “A Saccharomyces cerevisiae homologue of mammalian translation initiation factor 4B contributes to RNA helicase activity,” The EMBO Journal, vol. 12, no. 10, pp. 3997–4003, 1993.
[14]
N. Méthot, A. Pause, J. W. B. Hershey, and N. Sonenberg, “The translation initiation factor eIF-4B contains an RNA-binding region that is distinct and independent from its ribonucleoprotein consensus sequence,” Molecular and Cellular Biology, vol. 14, no. 4, pp. 2307–2316, 1994.
[15]
W. C. Merrick, “Eukaryotic protein synthesis: an in vitro analysis,” Biochimie, vol. 76, no. 9, pp. 822–830, 1994.
[16]
C. Wei, M. L. Balasta, J. Ren, and D. J. Goss, “Wheat germ poly(A) binding protein enhances the binding affinity of eukaryotic initiation factor 4F and (iso)4F for cap analogues,” Biochemistry, vol. 37, no. 7, pp. 1910–1916, 1998.
[17]
X. Bi, J. Ren, and D. J. Goss, “Wheat germ translation initiation factor eIF4B affects eIF4A and eIFiso4F helicase activity by increasing the ATP binding affinity of eIF4A,” Biochemistry, vol. 39, no. 19, pp. 5758–5765, 2000.
[18]
D. R. Gallie, W. J. Lucas, and V. Walbot, “Visualizing mRNA expression in plant protoplasts: factors influencing efficient mRNA uptake and translation,” The Plant Cell, vol. 1, no. 3, pp. 301–311, 1989.
[19]
D. R. Gallie, “The cap and poly(A) tail function synergistically to regulate mRNA translational efficiency,” Genes and Development, vol. 5, no. 11, pp. 2108–2116, 1991.
[20]
D. R. Gallie and V. Walbot, “RNA pseudoknot domain of tobacco mosaic virus can functionally substitute for a poly(A) tail in plant an animal cells,” Genes and Development, vol. 4, no. 7, pp. 1149–1157, 1990.
[21]
V. Leathers, R. Tanguay, M. Kobayashi, and D. R. Gallie, “A phylogenetically conserved sequence within viral 3′ untranslated RNA pseudoknots regulates translation,” Molecular and Cellular Biology, vol. 13, no. 9, pp. 5331–5347, 1993.
[22]
D. R. Gallie and M. Kobayashi, “The role of the 3′-untranslated region of non-polyadenylated plant viral mRNAs in regulating translational efficiency,” Gene, vol. 142, no. 2, pp. 159–165, 1994.
[23]
D. R. Gallie, R. L. Tanguay, and V. Leathers, “The tobacco etch viral 5′ leader and poly(A) tail are functionally synergistic regulators of translation,” Gene, vol. 165, no. 2, pp. 233–238, 1995.
[24]
D. R. Gallie, N. J. Lewis, and W. F. Marzluff, “The histone 3′-terminal stem-loop is necessary for translation in Chinese hamster ovary cells,” Nucleic Acids Research, vol. 24, no. 10, pp. 1954–1962, 1996.
[25]
J. Ling, S. J. Morley, V. M. Pain, W. F. Marzluff, and D. R. Gallie, “The histone 3′-terminal stem-loop-binding protein enhances translation through a functional and physical interaction with eukaryotic initiation factor 4G (eIF4G) and eIF3,” Molecular and Cellular Biology, vol. 22, no. 22, pp. 7853–7867, 2002.
[26]
I. M. Krab, C. Caldwell, D. R. Gallie, and J. F. Bol, “Coat protein enhances translational efficiency of Alfalfa mosaic virus RNAs and interacts with the eIF4G component of initiation factor eIF4F,” Journal of General Virology, vol. 86, no. 6, pp. 1841–1849, 2005.
[27]
H. Le, R. L. Tanguay, M. L. Balasta et al., “Translation initiation factors eIF-iso4G and eIF-4B interact with the poly(A)-binding protein and increase its RNA binding activity,” Journal of Biological Chemistry, vol. 272, no. 26, pp. 16247–16255, 1997.
[28]
S. Z. Tarun Jr. and A. B. Sachs, “Association of the yeast poly(A) tail binding protein with translation initiation factor eIF-4G,” EMBO Journal, vol. 15, no. 24, pp. 7168–7177, 1996.
[29]
H. Imataka, A. Gradi, and N. Sonenberg, “A newly identified N-terminal amino acid sequence of human eIF4G binds poly(A)-binding protein and functions in poly(A)-dependent translation,” The EMBO Journal, vol. 17, no. 24, pp. 7480–7489, 1998.
[30]
M. Piron, P. Vende, J. Cohen, and D. Poncet, “Rotavirus RNA-binding protein NSP3 interacts with eIF4GI and evicts the poly(A) binding protein from eIF4F,” EMBO Journal, vol. 17, no. 19, pp. 5811–5821, 1998.
[31]
C. S. Fraser, V. M. Pain, and S. J. Morley, “The association of initiation factor 4F with poly(A)-binding protein is enhanced in serum-stimulated Xenopus kidney cells,” The Journal of Biological Chemistry, vol. 274, no. 1, pp. 196–204, 1999.
[32]
M. Bushell, W. Wood, G. Carpenter, V. M. Pain, S. J. Morley, and M. J. Clemens, “Disruption of the interaction of mammalian protein synthesis initiation factor 4B with the poly(A) binding protein by caspase - and viral protease-mediated cleavages,” The Journal of Biological Chemistry, vol. 276, no. 26, pp. 23922–23928, 2001.
[33]
L. Bellsolell, P. F. Cho-Park, F. Poulin, N. Sonenberg, and S. K. Burley, “Two structurally atypical HEAT domains in the C-terminal portion of human eIF4G support binding to eIF4A and Mnk1,” Structure, vol. 14, no. 5, pp. 913–923, 2006.
[34]
J. Marcotrigiano, I. B. Lomakin, N. Sonenberg, T. V. Pestova, C. U. T. Hellen, and S. K. Burley, “A conserved HEAT domain within eIF4G directs assembly of the translation initiation machinery,” Molecular Cell, vol. 7, no. 1, pp. 193–203, 2001.
[35]
S. Cheng and D. R. Gallie, “Competitive and noncompetitive binding of eIF4B, eIF4A, and the poly(A) binding protein to wheat translation initiation factor eIFiso4G,” Biochemistry, vol. 49, no. 38, pp. 8251–8265, 2010.
[36]
S. Cheng and D. R. Gallie, “Eukaryotic initiation factor 4B and the poly(A)-binding protein bind eIF4G competitively,” Translation, vol. 1, no. 1, Article ID e24038, 13 pages, 2013.
[37]
C. Goyer, M. Altmann, H. S. Lee et al., “TIF4631 and TIF4632: two yeast genes encoding the high-molecular-weight subunits of the cap-binding protein complex (eukaryotic initiation factor 4F) contain an RNA recognition motif-like sequence and carry out an essential function,” Molecular and Cellular Biology, vol. 13, no. 8, pp. 4860–4874, 1993.
[38]
B. J. Lamphear, R. Kirchweger, T. Skern, and R. E. Rhoads, “Mapping of functional domains in eukaryotic protein synthesis initiation factor 4G (eIF4G) with picornaviral proteases. Implications for Cap-dependent and Cap-independent translational initiation,” Journal of Biological Chemistry, vol. 270, no. 37, pp. 21975–21983, 1995.
[39]
H. Imataka and N. Sonenberg, “Human eukaryotic translation initiation factor 4G (eIF4G) possesses two separate and independent binding sites for eIF4A,” Molecular and Cellular Biology, vol. 17, no. 12, pp. 6940–6947, 1997.
[40]
A. Marintchev and G. Wagner, “Translation initiation: structures, mechanisms and evolution,” Quarterly Reviews of Biophysics, vol. 37, no. 3-4, pp. 197–284, 2004.
[41]
D. R. Gallie and K. S. Browning, “eIF4G functionally differs from eIFiso4G in promoting internal initiation, cap-independent translation, and translation of structured mRNAs,” The Journal of Biological Chemistry, vol. 276, no. 40, pp. 36951–36960, 2001.
[42]
A. K. Lefebvre, N. L. Korneeva, M. Trutschl et al., “Translation initiation factor eIF4G-1 binds to eIF3 through the eIF3e subunit,” Journal of Biological Chemistry, vol. 281, no. 32, pp. 22917–22932, 2006.
[43]
N. Villa, A. Do, J. W. Hershey, and C. S. Fraser, “Human eukaryotic initiation factor 4G (eIF4G) protein binds to eIF3c, -d, and -e to promote mRNA recruitment to the ribosome,” The Journal of Biological Chemistry, vol. 288, no. 46, pp. 32932–32940, 2013.
[44]
N. L. Korneeva, B. J. Lamphear, F. L. C. Hennigan, and R. E. Rhoads, “Mutually cooperative binding of eukaryotic translation initiation factor (eIF) 3 and eIF4A to human eIF4G-1,” The Journal of Biological Chemistry, vol. 275, no. 52, pp. 41369–41376, 2000.
[45]
H. He, T. von der Haar, C. R. Singh et al., “The yeast eukaryotic initiation factor 4G (eIF4G) HEAT domain interacts with eIF1 and eIF5 and is involved in stringent AUG selection,” Molecular and Cellular Biology, vol. 23, no. 15, pp. 5431–5445, 2003.
[46]
C. R. Singh, R. Watanabe, W. Chowdhury et al., “Sequential eukaryotic translation initiation factor 5 (eIF5) binding to the charged disordered segments of eIF4G and eIF2β stabilizes the 48S preinitiation complex and promotes its shift to the initiation mode,” Molecular and Cellular Biology, vol. 32, no. 19, pp. 3978–3989, 2012.
[47]
Y. Yamamoto, C. R. Singh, A. Marintchev et al., “The eukaryotic initiation factor (eIF) 5 HEAT domain mediates multifactor assembly and scanning with distinct to interacts to eIF1, eIF2, eIF3, and eIF4G,” Proceedings of the National Academy of Sciences of the United States of America, vol. 102, no. 45, pp. 16164–16169, 2005.
[48]
A. Gradi, H. Imataka, Y. V. Svitkin et al., “A novel functional human eukaryotic translation initiation factor 4G,” Molecular and Cellular Biology, vol. 18, no. 1, pp. 334–342, 1998.
[49]
K. S. Browning, “The plant translational apparatus,” Plant Molecular Biology, vol. 32, no. 1-2, pp. 107–144, 1996.
[50]
I. B. Lomakin, C. U. T. Hellen, and T. V. Pestova, “Physical association of eukaryotic initiation factor 4G (EIF4G) with EIF4A strongly enhances binding of EIF4G to the internal ribosomal entry site of encephalomyocarditis virus and is required for internal initiation of translation,” Molecular and Cellular Biology, vol. 20, no. 16, pp. 6019–6029, 2000.
[51]
P. Schütz, M. Bumann, A. E. Oberholzer et al., “Crystal structure of the yeast eIF4A-eIF4G complex: an RNA-helicase controlled by protein—protein interactions,” Proceedings of the National Academy of Sciences of the United States of America, vol. 105, no. 28, pp. 9564–9569, 2008.
[52]
H. S. Yang, M. H. Cho, H. Zakowicz, G. Hegamyer, N. Sonenberg, and N. H. Colburn, “A novel function of the MA-3 domains in transformation and translation suppressor Pdcd4 is essential for its binding to eukaryotic translation initiation factor 4A,” Molecular and Cellular Biology, vol. 24, no. 9, pp. 3894–3906, 2004.
[53]
H. Le, K. S. Browning, and D. R. Gallie, “The phosphorylation state of poly(A)-binding protein specifies its binding to poly(A) RNA and its interaction with eukaryotic initiation factor (eIF) 4F, eIFiso4F, and eIF4B,” The Journal of Biological Chemistry, vol. 275, no. 23, pp. 17452–17462, 2000.
[54]
A. Z. Andreou and D. Klostermeier, “eIF4B and eIF4G jointly stimulate eIF4A ATPase and unwinding activities by modulation of the eIF4A conformational cycle,” Journal of Molecular Biology, vol. 426, pp. 51–61, 2014.
[55]
S. Lax, W. Fritz, K. Browning, and J. Ravel, “Isolation and characterization of factors from wheat germ that exhibit eukaryotic initiation factor 4B activity and overcome 7-methylguanosine 5'-triphosphate inhibition of polypeptide synthesis,” Proceedings of the National Academy of Sciences of the United States of America, vol. 82, no. 2, pp. 330–333, 1985.
[56]
S. R. Lax, K. S. Browning, D. M. Maia, and J. M. Ravel, “ATPase activities of wheat germ initiation factors 4A, 4B, and 4F,” Journal of Biological Chemistry, vol. 261, no. 33, pp. 15632–15636, 1986.
[57]
K. S. Browning, S. R. Lax, and J. M. Ravel, “Identification of two messenger RNA cap binding proteins in wheat germ. Evidence that the 28-kDa subunit of eIF-4B and the 26-kDa subunit of eIF-4F are antigenically distinct polypeptides,” The Journal of Biological Chemistry, vol. 262, no. 23, pp. 11228–11232, 1987.
[58]
K. S. Browning, L. Fletcher, S. R. Lax, and J. M. Ravel, “Evidence that the 59-kDa protein synthesis initiation factor from wheat germ is functionally similar to the 80-kDa initiation factor 4B from mammalian cells,” Journal of Biological Chemistry, vol. 264, no. 15, pp. 8491–8494, 1989.
[59]
G. W. Rogers Jr., N. J. Richter, and W. C. Merrick, “Biochemical and kinetic characterization of the RNA helicase activity of eukaryotic initiation factor 4A,” Journal of Biological Chemistry, vol. 274, no. 18, pp. 12236–12244, 1999.
[60]
G. W. Rogers Jr., N. J. Richter, W. F. Lima, and W. C. Merrick, “Modulation of the Helicase Activity of eIF4A by eIF4B, eIF4H, and eIF4F,” The Journal of Biological Chemistry, vol. 276, no. 33, pp. 30914–30922, 2001.
[61]
H. Trachsel, B. Erni, M. H. Schreier, and T. Staehelin, “Initiation of mammalian protein synthesis. II. The assembly of the initiation complex with purified initiation factors,” Journal of Molecular Biology, vol. 116, no. 4, pp. 755–767, 1977.
[62]
R. Benne and J. W. B. Hershey, “The mechanism of action of protein synthesis initiation factors from rabbit reticulocytes,” Journal of Biological Chemistry, vol. 253, no. 9, pp. 3078–3087, 1978.
[63]
M. Altmann, B. Wittmer, N. Methot, N. Sonenberg, and H. Trachsel, “The Saccharomyces cerevisiae translation initiation factor Tif3 and its mammalian homologue, eIF-4B, have RNA annealing activity,” The EMBO Journal, vol. 14, no. 15, pp. 3820–3827, 1995.
[64]
T. V. Pestova, I. N. Shatsky, and C. U. T. Hellen, “Functional dissection of eukaryotic initiation factor 4F: the 4A subunit and the central domain of the 4G subunit are sufficient to mediate internal entry of 43S preinitiation complexes,” Molecular and Cellular Biology, vol. 16, no. 12, pp. 6859–6869, 1996.
[65]
S. Morino, H. Imataka, Y. V. Svitkin, T. V. Pestova, and N. Sonenberg, “Eukaryotic translation initiation factor 4E (eIF4E) binding site and the middle one-third of eIF4GI constitute the core domain for cap-dependent translation, and the C-terminal one-third functions as a modulatory region,” Molecular and Cellular Biology, vol. 20, no. 2, pp. 468–477, 2000.
[66]
S. Cheng and D. R. Gallie, “Wheat eukaryotic initiation factor 4B organizes assembly of RNA and eIFiso4G, eIF4A, and poly(A)-binding protein,” The Journal of Biological Chemistry, vol. 281, no. 34, pp. 24351–24364, 2006.
[67]
F. Zhou, S. E. Walker, S. F. Mitchell, J. R. Lorsch, and A. G. Hinnebusch, “Identification and characterization of functionally critical, conserved motifs in the internal repeats and N-terminal domain of yeast translation initiation factor 4B (yeIF4B),” The Journal of Biological Chemistry, vol. 289, no. 3, pp. 1704–1722, 2014.
[68]
A. B. Sachs, R. W. Davis, and R. D. Kornberg, “A single domain of yeast poly(A)-binding protein is necessary and sufficient for RNA binding and cell viability,” Molecular and Cellular Biology, vol. 7, no. 9, pp. 3268–3276, 1987.
[69]
U. Kühn and T. Pieler, “XenopusPoly(A) binding protein: functional domains in RNA binding and protein—protein interaction,” Journal of Molecular Biology, vol. 256, no. 1, pp. 20–30, 1996.
[70]
S. H. Kessler and A. B. Sachs, “RNA recognition motif 2 of yeast Pab1p is required for its functional interaction with eukaryotic translation initiation factor 4G,” Molecular and Cellular Biology, vol. 18, no. 1, pp. 51–57, 1998.
[71]
L. J. Otero, M. P. Ashe, and A. B. Sachs, “The yeast poly(A)-binding protein Pab1p stimulates in vitro poly(A)-dependent and cap-dependent translation by distinct mechanisms,” EMBO Journal, vol. 18, no. 11, pp. 3153–3163, 1999.
[72]
S. Cheng and D. R. Gallie, “eIF4G, eIFiso4G, and eIF4B bind the poly(A)-binding protein through overlapping sites within the RNA recognition motif domains,” Journal of Biological Chemistry, vol. 282, no. 35, pp. 25247–25258, 2007.
[73]
K. Khaleghpour, Y. V. Svitkin, A. W. Craig et al., “Translational repression by a novel partner of human poly(A) binding protein, Paip2,” Molecular Cell, vol. 7, no. 1, pp. 205–216, 2001.
[74]
G. Roy, G. de Crescenzo, K. Khaleghpour, A. Kahvejian, M. O'Connor-McCourt, and N. Sonenberg, “Paip1 interacts with poly(A) binding protein through two independent binding motifs,” Molecular and Cellular Biology, vol. 22, no. 11, pp. 3769–3782, 2002.
[75]
N. Uchida, S. Hoshino, H. Imataka, N. Sonenberg, and T. Katada, “A novel role of the mammalian GSPT/eRF3 associating with poly(A)-binding protein in cap/poly(A)-dependent translation,” Journal of Biological Chemistry, vol. 277, no. 52, pp. 50286–50292, 2002.
[76]
N. Hosoda, T. Kobayashi, N. Uchida et al., “Translation termination factor eRF3 mediates mRNA decay through the regulation of deadenylation,” Journal of Biological Chemistry, vol. 278, no. 40, pp. 38287–38291, 2003.
[77]
M. Albrecht and T. Lengauer, “Survey on the PABC recognition motif PAM2,” Biochemical and Biophysical Research Communications, vol. 316, no. 1, pp. 129–138, 2004.
[78]
X. Wang and R. Grumet, “Identification and characterization of proteins that interact with the carboxy terminus of poly(A)-binding protein and inhibit translation in vitro,” Plant Molecular Biology, vol. 54, no. 1, pp. 85–98, 2004.
[79]
J. Bravo, L. Aguilar-Henonin, G. Olmedo, and P. Guzmán, “Four distinct classes of proteins as interaction partners of the PABC domain of Arabidopsis thaliana poly(A)-binding proteins,” Molecular Genetics and Genomics, vol. 272, no. 6, pp. 651–665, 2005.
[80]
N. Siddiqui, M. J. Osborne, D. R. Gallie, and K. Gehring, “Solution structure of the PABC domain from wheat poly (A)-binding protein: an insight into RNA metabolic and translational control in plants,” Biochemistry, vol. 46, no. 14, pp. 4221–4231, 2007.
[81]
S. Cheng, S. Sultana, D. J. Goss, and D. R. Gallie, “Translation initiation factor 4B homodimerization, RNA binding, and interaction with poly(A)-binding protein are enhanced by zinc,” Journal of Biological Chemistry, vol. 283, no. 52, pp. 36140–36153, 2008.
[82]
Y. M. Michel, D. Poncet, M. Piron, K. M. Kean, and A. M. Borman, “Cap-poly(A) synergy in mammalian cell-free extracts. Investigation of the requirements for poly(A)-mediated stimulation of translation initiation,” The Journal of Biological Chemistry, vol. 275, no. 41, pp. 32268–32276, 2000.
[83]
T. von der Haar, P. D. Ball, and J. E. G. McCarthy, “Stabilization of eukaryotic initiation factor 4E binding to the mRNA 5′-cap by domains of eIF4G,” The Journal of Biological Chemistry, vol. 275, no. 39, pp. 30551–30555, 2000.
[84]
A. Kahvejian, Y. V. Svitkin, R. Sukarieh, M. M'Boutchou, and N. Sonenberg, “Mammalian poly(A)-binding protein is a eukaryotic translation initiation factor, which acts via multiple mechanisms,” Genes and Development, vol. 19, no. 1, pp. 104–113, 2005.
[85]
T. M. Hinton, M. J. Coldwell, G. A. Carpenter, S. J. Morley, and V. M. Pain, “Functional analysis of individual binding activities of the scaffold protein eIF4G,” The Journal of Biological Chemistry, vol. 282, no. 3, pp. 1695–1708, 2007.
[86]
Y. Luo and D. J. Goss, “Homeostasis in mRNA initiation: wheat germ poly(A)-binding protein lowers the activation energy barrier to initiation complex formation,” The Journal of Biological Chemistry, vol. 276, no. 46, pp. 43083–43086, 2001.
[87]
M. A. Khan and D. J. Goss, “Translation initiation factor (eIF) 4B affects the rates of binding of the mRNA m7G cap analogue to wheat germ eIFiso4F and eIFiso4F·PABP,” Biochemistry, vol. 44, no. 11, pp. 4510–4516, 2005.
[88]
N. Amrani, S. Ghosh, D. A. Mangus, and A. Jacobson, “Translation factors promote the formation of two states of the closed-loop mRNP,” Nature, vol. 453, no. 7199, pp. 1276–1280, 2008.
[89]
Y. V. Svitkin, V. M. Evdokimova, A. Brasey et al., “General RNA-binding proteins have a function in poly(A)-binding protein-dependent translation,” EMBO Journal, vol. 28, no. 1, pp. 58–68, 2009.
[90]
S. E. Wells, P. E. Hillner, R. D. Vale, and A. B. Sachs, “Circularization of mRNA by eukaryotic translation initiation factors,” Molecular Cell, vol. 2, no. 1, pp. 135–140, 1998.
[91]
N. Iizuka, L. Najita, A. Franzusoff, and P. Sarnow, “Cap-dependent and cap-independent translation by internal initiation of mRNAs in cell extracts prepared from Saccharomyces cerevisiae,” Molecular and Cellular Biology, vol. 14, no. 11, pp. 7322–7330, 1994.
[92]
S. Z. Tarun Jr. and A. B. Sachs, “A common function for mRNA 5' and 3' ends in translation initiation in yeast,” Genes and Development, vol. 9, no. 23, pp. 2997–3007, 1995.
[93]
D. R. Gallie, “The role of the initiation surveillance complex in promoting efficient protein synthesis,” Biochemical Society Transactions, vol. 32, no. 4, pp. 585–588, 2004.
[94]
B. W. Baer and R. D. Kornberg, “Repeating structure of cytoplasmic poly(A)-ribonucleoprotein.,” Proceedings of the National Academy of Sciences of the United States of America, vol. 77, no. 4, pp. 1890–1892, 1980.
[95]
N. Méthot, M. S. Song, and N. Sonenberg, “A region rich in aspartic acid, arginine, tyrosine, and glycine (DRYG) mediates eukaryotic initiation factor 4B (eIF4B) self-association and interaction with eIF3,” Molecular and Cellular Biology, vol. 16, no. 10, pp. 5328–5334, 1996.
[96]
H. Park, K. S. Browning, T. Hohn, and L. A. Ryabova, “Eucaryotic initiation factor 4B controls eIF3-mediated ribosomal entry of viral reinitiation factor,” EMBO Journal, vol. 23, no. 6, pp. 1381–1391, 2004.
[97]
J. Drawbridge, J. L. Grainger, and M. M. Winkler, “Identification and characterization of the poly(A)-binding proteins from the sea urchin: a quantitative analysis,” Molecular and Cellular Biology, vol. 10, no. 8, pp. 3994–4006, 1990.
[98]
D. R. Gallie, H. Le, C. Caldwell, R. L. Tanguay, N. X. Hoang, and K. S. Browning, “The phosphorylation state of translation initiation factors is regulated developmentally and following heat shock in wheat,” The Journal of Biological Chemistry, vol. 272, no. 2, pp. 1046–1053, 1997.
[99]
D. C. Schwartz and R. Parker, “Interaction of mRNA translation and mRNA degradation in Saccharomyces cerevisiae,” in Translational Control of Gene Expression, N. Sonenberg, J. W. B. Hershey, and M. B. Mathews, Eds., pp. 807–825, Cold Spring Harbor Press, New York, NY, USA, 2000.
[100]
H. Le, S. Chang, R. L. Tanguay, and D. R. Gallie, “The wheat poly(A)-binding protein functionally complements pab1 in yeast,” European Journal of Biochemistry, vol. 243, no. 1-2, pp. 350–357, 1997.
[101]
R. Duncan and J. W. B. Hershey, “Regulation of initiation factors during translational repression caused by serum depletion. Covalent modification,” The Journal of Biological Chemistry, vol. 260, no. 9, pp. 5493–5497, 1985.
[102]
R. F. Duncan and J. W. B. Hershey, “Protein synthesis and protein phosphorylation during heat stress, recovery, and adaptation,” Journal of Cell Biology, vol. 109, no. 4, pp. 1467–1481, 1989.
[103]
J. M. Manzella, W. Rychlik, R. E. Rhoads, J. W. B. Hershey, and P. J. Blackshear, “Insulin induction of ornithine decarboxylase: importance of mRNA secondary structure and phosphorylation of eucaryotic initiation factors eIF-4B and eIF-4E,” The Journal of Biological Chemistry, vol. 266, no. 4, pp. 2383–2389, 1991.
[104]
M. Wakiyama, H. Imataka, and N. Sonenberg, “Interaction of elF4G with poly(A)-binding protein stimulates translation and is critical for Xenopus oocyte maturation,” Current Biology, vol. 10, no. 18, pp. 1147–1150, 2000.
[105]
I. K. Ali, L. McKendrick, S. J. Morley, and R. J. Jackson, “Truncated initiation factor eIF4G lacking an eIF4E binding site can support capped mRNA translation,” EMBO Journal, vol. 20, no. 15, pp. 4233–4242, 2001.
[106]
D. R. Gallie, “The 5′-leader of tobacco mosaic virus promotes translation through enhanced recruitment of elF4F,” Nucleic Acids Research, vol. 30, no. 15, pp. 3401–3411, 2002.
