EFFECTS OF CORRELATIONS DURING RIBOSOME MOVEMENT ALONG mRNA

Motivation: During translation, ribosomes move linearly along mRNA. In this process, a simultaneous presence of two ribosomes at one codon is impossible; however, this fact is disregarded in all the known models of translation. In other words, the concentration of ribosomes on mRNA is conventionally considered small, that is, the translation is assumed inefficient. Results: The problem of stationary movement of the ribosome pool of the length L along the mRNA consisting of N codons is solved exactly by methods of statistical mechanics for 1<<L<<N. Mutual correlations of the ribosome movement yield three qualitatively distinct phases. Realization of a phase depends on what process—initiation, termination, or elongation—controls the translation process; hence, it is feasible to detect the limiting phase from the pattern of ribosome distribution along mRNA. The model proposed can be easily restated for any case of a linear transport of ribosomes (for example, their scanning of 5’UTRs). Dispersion of the ribosome codon reading speeds is considered for the case of shock translation