Translation prokaryotes

Brandi, L., Fabbretti, A., La Teana, A., Abbondi, M., Losi, D., Donadio, S., and Gualerzi, C. O. (2006b). Specific, efficient, and selective inhibition of prokaryotic translation initiation by a novel peptide antibiotic. Proc. Nat. Acad. Sci. USA 103, 39-44. 

Kolb, V. A., Makeyev, E. V., and Spirin, A. S. (2000). Co-translational folding of a eukaryotic multidomain protein in a prokaryotic translation system. J. Biol. Chem. 275, 16597-16601. 

Some well-known inhibitors of prokaryotic translation include streptomycin, erythromycin, tetracydine, and chloramphenicol. Inhibitors of eukaryotic translation include cycloheximide and Diphtheria and Pseudomonas toxins. 

Abbreviations aa-tRNA Amino-acyl tRNA eLF Eukaryotic translation initiation factor IF Prokaryotic translation initiation factor eEF Eukaryotic translation elongation factor EF Prokaryotic translation elongation factor eRF Eukaryotic translation termination factor (release factor) RF Prokaryotic translation release factor RRF Ribosome recycling factor Rps Protein of the prokaryotic small ribosomal subunit Rpl Protein of the eukaryotic large ribosomal subunit S Protein of the prokaryotic small ribosomal subunit L Protein of the prokaryotic large ribosomal subunit PTC Peptidyl transferase center RNC Ribosome-nascent chain-mRNA complex ram Ribosomal ambiguity mutation RAC Ribosome-associated complex NMD Nonsense-mediated mRNA decay... 

The selection of transformed chloroplasts usually involves the use of an antibiotic resistance marker. Spectinomycin is used most routinely because of the high specificity it displays as a prokaryotic translational inhibitor as well as the relatively low side effects it exerts on plants. The bacterial aminoglycoside 3 -adenyltransferase gene (ciadA) confers resistance to both streptomycin and spectinomycin. The aadA protein catalyzes the covalent transfer of an adenosine monophosphate (AMP) residue from adenosine triphosphate (ATP) to spectinomycin, thereby converting the antibiotic into an inactive form that no longer inhibits protein synthesis for prokaryotic 70S ribosomes that are present in the chloroplast. 

Ueda, T., Tohda, H., Chikazumi, N., Eckstein, F. and Watanabe, K. (1991) Phosphorothioate-containing RNAs show mRNA activity in the prokaryotic translation systems in vitro. Nucleic Acids Res., 19, 547-552. 

The mRNA required for in vitro translation can itself be produced by in vitro synthesis. Commercially available kits allow DNA cloned downstream of T7-, T3 or SP6-promoters to be transcribed effectively in vitro by the relevant RNA polymerases. In coupled transcription-translation, it should be remembered that translation of eukaryotic mRNA requires a 5 cap upstream of the initiation codon, and similarly, for prokaryotic translation there should be an appropriately positioned ribosome binding site. Commercial kits are also available for combined in vitro transcription and translation. 

The structure resembles that of a tRNA by molecular mimicry. The sequence Gly-Gly-Gln, present in both eukaryotes and prokaryotes, occurs at the end of the structure corresponding to the acceptor stem of a tRNA. This region binds a water molecule. Disguised as an aminoacyl-tRNA, the release factor may carry this water molecule into the peptidyl transferase center and, assisted by the catalytic apparatus of the ribosome, promote this water molecule s attack on the ester linkage, freeing the polypeptide chain. The detached polypeptide leaves the ribosome. Transfer RNA and messenger RNA remain briefly attached to the 70S ribosome until the entire complex is dissociated in a GTP-dependent fashion by ribosome release factor (RRF) and EF-G. Ribosome release factor is an essential factor for prokaryotic translation. 

In prokaryotic translation, where die initiation codon interacts with the anticodon of f-Met-tRNAfmet, what is the sequence of the anticodon ... 

What are the major differences between eukaryotic and prokaryotic translation ... 

The major differences between prokaryotic and eukaryotic translation are speed (the prokaryotic process is significandy faster), locadon (the eukaryotic process is not direcdy coupled to tran-scripdon as prokaryotic translation is), complexity (because of their complex life styles, eukaryotes possess complex mechanisms for regulatory protein synthesis, e.g., eukaryodc transla-don involves a significandy larger number of protein factors than prokaryotic translation), and post translational modifications (eukaryotic reactions appear to be considerably more complex and varied than those observed in prokaryotes.)... 

Peptide deformylase is involved in deformylation of the formyl-methionyl derivatives of proteins formed in the prokaryotic translational systems, and thus its inhibitors are searched as candidates for new antibiotic drugs (133). The active peptide deformylase has Fe(ll) ion in the active site, which reacts readily with oxygen. To obtain a stable variant, the Fe(ll) ion is often substituted with Zn(II), although Zn(II)-peptide deformylase has reduced activity by two to three orders of magnitude. Escherichia coli Zn(ll)-peptide deformylase was used as the target enzyme in this study. 

See also Translation Overview, Eukaryotic vs Prokaryotic Translation, Figure 27.15, Stringent Response, Posttranscriptional Processing of rRNA and tRNA... 

See also The Genetic Code, Structure of tRNAs, Initiation of Translation, Prokaryotic Translation Regulation, Lactose Operon Regulation (from Chapter 26), Promoter Organization... 

See also Initiation of Translation, Structure of tRNAs, Structure of Prokaryotic mRNAs, Termination of Translation, Eukaryotic vs Prokaryotic Translation (from Chapter 28)... 

Initiation of prokaryotic translation is depicted in Figure 27.20. Steps include ... 

Inhibitors of translation - A number of the common inhibitors of prokaryotic translation are also effective in eukaryotic cells. They include pactamycin, tetracycline, and puromycin. Inhibitors that are effective only in eukaryotes include cycloheximide and diphtheria toxin. Cycloheximide inhibits the peptidyltransferase activity of the eukaryotic ribosome. Diphtheria toxin is an enzyme, coded for by a bacteriophage that is lysogenic in the bacterium Corynebacterium diphtheriae. It catalyzes a reaction in which NAD+ adds an ADP ribose group to a specially modified histidine in the translocation factor eEF2, the eukaryotic equivalent of EF-G (Figure 28.36). Because the toxin is a catalyst, minute amounts can irreversibly block a cell s protein synthetic machinery. As a result, pure diphtheria toxin is one of the most deadly substances known. 

The 3 phosphorothioate residues, introduced by the phosphoramidite method, were shown to significantly protect the oligomer from the action of nucleases. This hybrid, in which the ribonucleotide portion is complementary to the leader sequence of phage fl coat protein mRNA, was used to study the formation of the initiation complex in prokaryotic translation. 

How does the ribosome know where to start translating In prokaryotic translation, the correct AUG start codon is identified by its proximity to a consensus sequence called the Shine-Dalgarno sequence. This sequence is complementary to a sequence on the small subunit of the prokaryotic ribosome. The ribosome is initially positioned on the Shine-Dalgarno sequence, which aligns it for correct translation initiation at the start codon. 

Match the functions or characteristics of prokaryotic translation in the right column with the appropriate translation components in the left column. 

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