Berlin 2012 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 13: DNA/RNA and Related Enzymes

BP 13.2: Vortrag

Mittwoch, 28. März 2012, 10:00–10:15, H 1058

The Speed of Ribosomes — •Sophia Rudorf, Angelo Valleriani, and Reinhard Lipowsky — Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Am Mühlenberg 1, 14476 Potsdam

To synthesize a protein a ribosome moves along the codons of a messenger RNA (mRNA) and takes up corresponding aminoacylated transfer RNAs (aa-tRNAs). During this process called translation elongation the ribosome does not always proceed at the same speed. Here we present an analytical model to calculate codon-specific elongation rates based on aa-tRNA concentrations and codon usages. The model takes into account non-cognate aa-tRNAs that compete with cognate aa-tRNAs as well as the number of translating ribosomes. Using available in vivo data and codon usages obtained from mRNA Deep Sequencing we computed the elongation rates for Escherichia coli. Results of stochastic simulations based on these elongation rates coincide well with experimental data. We found that increasing the number of translating ribosomes strongly decreases the availability of frequently used aa-tRNAs. This leads to comparably low elongation rates of some abundant codons, in contrast to the generally high correlation of elongation rates and codon usages.