Turnover of messenger RNA: Polysome statistics beyond the steady state

¹  Max Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems Potsdam, Germany, EU
²  University of Potsdam, Institute of Biochemistry and Biology - Potsdam, Germany, EU

Corresponding author: valleriani@mpikg.mpg.de

Received: 14 August 2009
Accepted: 17 February 2009

Abstract

The interplay between turnover or degradation and ribosome loading of messenger RNA (mRNA) is studied theoretically using a stochastic model that is motivated by recent experimental results. Random mRNA degradation affects the statistics of polysomes, i.e., the statistics of the number of ribosomes per mRNA as extracted from cells. Since ribosome loading of newly created mRNA chains requires some time to reach steady state, a fraction of the extracted mRNA/ribosome complexes does not represent steady state conditions. As a consequence, the mean ribosome density obtained from the extracted complexes is found to be inversely proportional to the mRNA length. On the other hand, the ribosome density profile shows an exponential decrease along the mRNA for prokaryotes and becomes uniform in eukaryotic cells.