Induced fit of a peptide loop of methionyl-tRNA formyltransferase triggered by the initiator tRNA substrate

Mayer, Christine; Dyson, Michael R.; Gite, Sadanand; RajBhandary, Uttam L.

doi:10.1073/pnas.96.3.875

Cited by 16 publications

(20 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This provides the tRNA with a 5-nucleotide single-stranded 3Ј end of the acceptor arm just long enough to reach the active site of MTF (197). Both the initiator tRNA and MTF undergo structural changes in an induced-fit mechanism upon binding (122,181). The regions on Met-tRNA f Met that interact with MTF are shown in Fig.…”

Section: Initiator Trnamentioning

confidence: 99%

Initiation of Protein Synthesis in Bacteria

Laursen

Sørensen

Mortensen

et al. 2005

Microbiol Mol Biol Rev

530

506

View full text Add to dashboard Cite

Valuable information on translation initiation is available from biochemical data and recently solved structures. We present a detailed description of current knowledge about the structure, function, and interactions of the individual components involved in bacterial translation initiation. The first section describes the ribosomal features relevant to the initiation process. Subsequent sections describe the structure, function, and interactions of the mRNA, the initiator tRNA, and the initiation factors IF1, IF2, and IF3. Finally, we provide an overview of mechanisms of regulation of the translation initiation event. Translation occurs on ribonucleoprotein complexes called ribosomes. The ribosome is composed of a large subunit and a small subunit that hold the activities of peptidyltransfer and decode the triplet code of the mRNA, respectively. Translation initiation is promoted by IF1, IF2, and IF3, which mediate base pairing of the initiator tRNA anticodon to the mRNA initiation codon located in the ribosomal P-site. The mechanism of translation initiation differs for canonical and leaderless mRNAs, since the latter is dependent on the relative level of the initiation factors. Regulation of translation occurs primarily in the initiation phase. Secondary structures at the mRNA ribosomal binding site (RBS) inhibit translation initiation. The accessibility of the RBS is regulated by temperature and binding of small metabolites, proteins, or antisense RNAs. The future challenge is to obtain atomic-resolution structures of complete initiation complexes in order to understand the mechanism of translation initiation in molecular detail

show abstract

Section: Initiator Trnamentioning

confidence: 99%

Initiation of Protein Synthesis in Bacteria

Laursen

Sørensen

Mortensen

et al. 2005

Microbiol Mol Biol Rev

530

506

View full text Add to dashboard Cite

show abstract

“…This was further supported by mutational analyses which identified residues in the N‐terminal domain that are involved in catalysis [12]. In addition, a loop region between β‐strand 2 and α‐helix 2 of this domain has been shown to play an important role in discriminating between the initiator and elongator tRNAs [17–19]. The C‐terminal domain is also involved in tRNA binding.…”

Section: Introductionmentioning

confidence: 79%

“…2). Several residues in the E. coli MTF that have been shown to be important for tRNA fMet binding, are also conserved in the P. aeruginosa enzyme [18–20]. These include Gly‐42, Arg‐43, Lys‐210, Gly‐291, Asp‐299, Arg‐304 and Arg‐305 (Fig.…”

Section: Resultsmentioning

confidence: 99%

Recognition of the initiator tRNA by thePseudomonas aeruginosamethionyl-tRNA formyltransferase: importance of the base-base mismatch at the end of the acceptor stem

Newton

Niemkiewicz

et al. 1999

FEMS Microbiology Letters

View full text Add to dashboard Cite

Formylation of the initiator methionyl-tRNA (Met-tRNAfMet) in eubacteria is catalyzed by methionyl-tRNA formyltransferase (MTF). Features of the Escherichia coli tRNAfMet that are important for formylation are the base-base mismatch between nucleotides 1 and 72, and the second and third base pairs of the acceptor stem. The base-base mismatch is the most crucial formylation determinant in the E. coli tRNAfMet. However, it is not known whether this feature is also important for formylation of other eubacterial tRNAfMet. We cloned the Pseudomonas aeruginosa MTF gene by complementation of an E. coli MTF mutant strain with a genomic library, and investigated the catalytic properties and substrate specificity of the enzyme. The results show that the P. aeruginosa and E. coli enzymes have comparable affinities for the tRNAfMet and N10-formyltetrahydrofolate (fTHF) substrates. Overproduction of the P. aeruginosa MTF rescued the initiator activity of an E. coli formylation-defective tRNAfMet with a base pair between nucleotides 1 and 72, indicating that the base-base mismatch is utilized by the P. aeruginosa MTF for recognition of the tRNAfMet. Therefore, this feature may be used by MTFs from other eubacteria to distinguish the initiator from elongator tRNAs.

show abstract

“…Previous studies had shown that introduction of the polyhistidine tag does not affect the activity of MTF (44). The R42L mutant MTF is ϳ1,400-fold less active in formylation of the E. coli initiator tRNA (45,46) and is used as a negative control here.…”

Section: Resultsmentioning

confidence: 99%

“…Second, there are important differences between the eubacterial MTFs and the mammalian mitochondrial MTFs (56). The eubacterial MTFs have a highly conserved arginine residue present in a flexible loop that is critical for the activity of MTF (45,46,49), whereas mammalian mitochondrial MTF does not have the arginine residue. Therefore, it is quite possible that drugs targeted against eu-bacterial MTFs will not have any effect on mammalian mitochondrial MTFs.…”

Section: Discussionmentioning

confidence: 99%

Expression of Escherichia coli Methionyl-tRNA Formyltransferase in Saccharomyces cerevisiae Leads to Formylation of the Cytoplasmic Initiator tRNA and Possibly to Initiation of Protein Synthesis with Formylmethionine

Köhrer

RajBhandary

2002

Molecular and Cellular Biology

Self Cite

View full text Add to dashboard Cite

Protein synthesis in eukaryotic cytoplasm and in archaebacteria is initiated with methionine, whereas, that in eubacteria and in eukaryotic organelles, such as mitochondria and chloroplasts, is initiated with formylmethionine. In view of this clear distinction, we have investigated whether protein synthesis in the eukaryotic cytoplasm can be initiated with formylmethionine, and, if so, what the consequences are to the cell. For this purpose, we have expressed in an inducible manner the Escherichia coli methionyl-tRNA formyltransferase (MTF) in the cytoplasm of the yeast Saccharomyces cerevisiae. Expression of active MTF, but not of an inactive mutant, leads to formylation of methionine attached to the yeast cytoplasmic initiator tRNA to the extent of about 70%. As a consequence, the yeast strain grows slowly. Coexpression of the E. coli polypeptide deformylase (DEF), which removes the formyl group from the N-terminal formylmethionine in a polypeptide, rescues the slow-growth phenotype, whereas, coexpression of an inactive mutant of DEF does not. These results suggest that the cytoplasmic protein-synthesizing system of yeast, like that of eubacteria, can at least to some extent utilize formylated initiator Met-tRNA to initiate protein synthesis and that initiation of proteins with formylmethionine leads to the slow-growth phenotype. Removal of the formyl group in these proteins by DEF would explain the rescue of the slow-growth phenotype.Protein synthesis in eubacteria, mitochondria, and chloroplasts is initiated with formylmethionine (20,21,41). Of the two classes of methionine tRNAs present in eubacteria, mitochondria, and chloroplasts, tRNA Met and tRNA f Met , the initiator methionyl-tRNA (Met-tRNA f Met ) is specifically formylated by the enzyme methionyl-tRNA formyltransferase (MTF) to generate formylmethionyl-tRNA (fMet-tRNA f Met ). The formyl group acts as a positive determinant for selection of the fMet-tRNA f Met by the initiation factor IF2 (54) and as a second negative determinant for blocking the binding of the tRNA to the elongation factor. Formylation of the initiator Met-tRNA f Met is important for protein synthesis in Escherichia coli, mutant initiator tRNAs defective in formylation are extremely poor in initiation of protein synthesis, and a strain of E. coli carrying disruptions in the MTF gene has severe growth defects (12,33,59).In contrast to the situation with eubacteria, mitochondria, and chloroplasts presented above, in the cytoplasm of eukaryotes and in archaebacteria, there is no formylation of the initiator tRNA (tRNA i Met ), and the Met-tRNA i Met is utilized directly to initiate protein synthesis with methionine (42, 47). However, the cytoplasmic initiator Met-tRNA i Met of yeast contains some of the determinants in the tRNA (Fig. 1) important for recognition by E. coli MTF (12a, 23) and can therefore be formylated in vitro by E. coli MTF (43). The resulting fMet-tRNA i Met initiates protein synthesis in cell extracts of both E. coli and rabbit reticulocytes, suggesting that the eu...

show abstract

Induced fit of a peptide loop of methionyl-tRNA formyltransferase triggered by the initiator tRNA substrate

Cited by 16 publications

References 51 publications

Initiation of Protein Synthesis in Bacteria

Initiation of Protein Synthesis in Bacteria

Recognition of the initiator tRNA by thePseudomonas aeruginosamethionyl-tRNA formyltransferase: importance of the base-base mismatch at the end of the acceptor stem

Expression of Escherichia coli Methionyl-tRNA Formyltransferase in Saccharomyces cerevisiae Leads to Formylation of the Cytoplasmic Initiator tRNA and Possibly to Initiation of Protein Synthesis with Formylmethionine

Contact Info

Product

Resources

About