Fidelity factors affecting

Proteins interacting with translation termination factors affect the fidelity of translation termination... 

What factors affect the choice about which translesion synthesis DNA polymerase will insert opposite a particular lesion Several lines of evidence suggest that E. coli has a hierarchy for the replication of normal, unadducted DNA when Pol III is inactivated Pol II > IV > V [104]. (The assays did not permit an assessment of Pol I.) Since this order (III > II > IV > V) does not reflect the relative concentration of these DNA polymerases in cells (see above), another mechanism for decision making was suggested, such as relative DNA polymerase affinity for the P-clamp. This order does reflect relative fidelity of these DNA polymerases and would be a sensible order for E. coli to allow translesion synthesis DNA polymerases to initially sample adducts/lesions prior to a decision about which polymerase will perform translesion synthesis. However, the ultimate decision is probably predominantly controlled by which translesion synthesis DNA polymerase is most efficient at bypassing a particular adduct/lesion biochemically. 

Several fluorescence and biochemical experiments reveal the detailed mechanism of translation and the contribution of KPR towards the fidelity of protein synthesis. The incorporation of an amino acid into the peptide is composed of two consecutive processes initial selection of tRNA at the A site of the ribosome followed by KPR [23]. Various factors affect the initial selection of tRNA such as the HB energy between the codon-anticodon base pairs, the specific interactions between the large subunit of the ribosome and aa-tRNA, etc. The contribution of the initial selection step to the overall error fraction for Escherichia coli is observed to be -1/6, compared to the overall error fraction -7 x 10 for cognate and near-cognate anticodons. As a consequence the contribution of KPR is expected to be 1/24 i.e. -80% of the observed fidelity comes from the KPR. The translation process occurs through the following mechanism (see Figure 13.2). 

Bacteria and eucarya are differentially affected by antibiotics that impair ribosome function (and/or fidelity) by directly interacting with, or by perturbing, functionally essential domains of ribosomes and factors. On the basis of their specificity, ribosome-directed and elongation factor-directed antibiotics have been classically subdivided into... 

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