Interaction of bacterial initiation factor 2 with initiator tRNA.

Sundari, R M; Stringer, Evan A.; Schulman, LaDonne H.; Maitra, Umadas

doi:10.1016/s0021-9258(17)33442-7

Cited by 94 publications

(21 citation statements)

References 43 publications

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“…The present in vitro mischarging studies show that tRNA™6'(GAC) and tRNA™6'(GAA) are less efficiently aminoacylated by valyl-and phenylalanyl-tRNA synthetases than wild-type cognate tRNAs (Figure 2). In addition, previous studies have shown that both E. coli transformylase and initiation factor 2 prefer methionine to non-methionine amino acids (Giege et al, 1973a,b;Sundari et al, 1976); thus, a combination of reduced efficiency in several steps in the initiation pathway is likely to contribute to the lower level of protein synthesized in the presence of the mutant initiator tRNAs. Little is known about the amino acid requirement for initiation of protein synthesis in eukaryotic systems; however, in vitro experiments have indicated that eukaryotic IF-2 strongly discriminates against the mammalian initiator tRNA when it is mischarged with isoleucine (Wagner et al, 1984), suggesting that higher organisms may have evolved in a manner that more strictly prohibits the use of non-methionine amino acids in the initiation pathway.…”

Section: Discussionmentioning

confidence: 99%

Initiation of in vivo protein synthesis with non-methionine amino acids

Chattapadhyay

Pelka²,

Schulman³

1990

Biochemistry

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Methionine is the universal amino acid for initiation of protein synthesis in all known organisms. The amino acid is coupled to a specific initiator methionine tRNA by methionyl-tRNA synthetase. In Escherichia coli, attachment of methionine to the initiator tRNA (tRNA(fMet)) has been shown to be dependent on synthetase recognition of the methionine anticodon CAU (complementary to the initiation codon AUG), [Schulman, L. H., & Pelka, H. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 6755-6759]. We show here that alteration of the anticodon of tRNA(fMet) to GAC or GAA leads to aminoacylation of the initiator tRNA with valine or phenylalanine. In addition, tRNA(fMet) carrying these amino acids initiates in vivo protein synthesis when provided with initiation codons complementary to the modified anticodons. These results indicate that the sequence of the anticodon of tRNA(fMet) dictates the identity of the amino acid attached to the initiator tRNA in vivo and that there are no subsequent steps which prevent initiation of E. coli protein synthesis by valine and phenylalanine. The methods described here also provide a convenient in vivo assay for further examination of the role of the anticodon in tRNA amino acid acceptor identity.

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Section: Discussionmentioning

confidence: 99%

Initiation of in vivo protein synthesis with non-methionine amino acids

Chattapadhyay

Pelka²,

Schulman³

1990

Biochemistry

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“…For IF-2 its, albeit weak, affinity for N-blocked aminoacyl-tRNA (Majumdar et al, 1976;Sundari et al, 1976;Leon et al, 1979;Petersen et al, 1979) might suggest a direct effect of the factor on the ribosome-bound ¿V-AcPhe-tRNA. On the other hand, it has been shown that IF-2 binding does not increase the affinity of the nonprogrammed 30S ribosomal subunit for either Ar-AcPhe-tRNAphe or fMet-tRNAf1'1 ; C. L. Pon and C. Gualerzi, unpublished results), making unlikely an appreciable binding interaction between IF-2 and N-blocked aminoacyl-tRNA on the ribosome.…”

Section: Discussionmentioning

confidence: 99%

Effect of Escherichia coli initiation factors on the kinetics of N-AcPhe-tRNAPhe binding to 30S ribosomal subunits. A fluorescence stopped-flow study

Wintermeyer¹,

Gualerzi²

1983

Biochemistry

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The mechanism of binding of N-AcPhe-tRNAPhe (yeast) to poly(U)-programmed Escherichia coli 30S ribosomal subunits and the effect of individual initiation factors (IF-1, IF-2, and IF-3) and GTP on this process have been studied by fluorescence stopped-flow kinetic measurements. The formation of the ternary complex was followed by an increase of both intensity and polarization of the fluorescence of a proflavin label located in the anticodon loop of the tRNA. The effect of the initiation factors and GTP is to increase the velocity of ternary complex formation (about 400-fold at 7 mM Mg2+). In the presence of the three initiation factors and GTP the formation of the ternary complex could be resolved into two partial reactions: a fast apparently second-order step (k12 = 5 x 10(6) M-1 s-1, k21 = 1.4 s-1) followed by a slow rearrangement step (k23 less than or equal to 0.1 s-1). The data suggest a mechanism in which the ternary complex is formed by at least two rearrangements of an initially formed preternary complex. The accelerating effects of both IF-2 and IF-3 can be understood by assuming a synergistic allosteric action of the factors on the 30S ribosomal subunit, whereas IF-1 appears to act indirectly by influencing the other two factors.

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“…IF2 is responsible for recognition of the formyl group of fMet-tRNA fMet (Antoun et al, 2006b;Majumdar et al, 1976;Sundari et al, 1976). IF2 in the GTP form promotes the recruitment of fMet-tRNA fMet to the 30S PIC (Milon et al, 2010) and ensures adjustment of initiator tRNA in the ribosomal P-site (Antoun et al, 2006b;Lockwood et al, 1971;La Teana et al, 1996) and mRNA restructuring during the formation of 30S IC (Studer and Joseph, 2006).…”

Section: Functions In Initiationmentioning

confidence: 99%

“…The presence of the formyl group is an important determinant which distinguishes initiator from elongator tRNAs (Kozak, 1999;RajBhandary, 1994). The formyl group attached to methionine on the tRNA fMet favors selection of fMet-tRNA fMet by IF2 (Sundari et al, 1976) and prevents its binding to EF-Tu (Hansen et al, 1986;Nissen et al, 1995;Seong and RajBhandary, 1987). In most cases formylated methionine is removed from the polypeptide chain after the translation has started (Bingel-Erlenmeyer et al, 2008;Bonissone et al, 2013;Kozak, 1983).…”

Section: Initiator Trnamentioning

confidence: 99%

Kinetic Dissection of Translation Initiation in Prokaryotes.

Filonava¹

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Interaction of bacterial initiation factor 2 with initiator tRNA.

Cited by 94 publications

References 43 publications

Initiation of in vivo protein synthesis with non-methionine amino acids

Initiation of in vivo protein synthesis with non-methionine amino acids

Effect of Escherichia coli initiation factors on the kinetics of N-AcPhe-tRNAPhe binding to 30S ribosomal subunits. A fluorescence stopped-flow study

Kinetic Dissection of Translation Initiation in Prokaryotes.

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