Berlin 2012 – scientific programme
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BP: Fachverband Biologische Physik
BP 22: Statistical Physics of Biological Systems III (with DY)
BP 22.4: Talk
Thursday, March 29, 2012, 15:45–16:00, H 1058
Buffering of the intracellular ribosome pool and protein production by ribosomal queues — •Philip Greulich1, Luca Ciandrini2, Mamen C. Romano2, and Rosalind J. Allen1 — 1ICMCS, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom — 2Institute for Complex Systems and Mathematical Biology, King's College, University of Aberdeen, Aberdeen, United Kingdom
In cells, mRNAs compete for a finite number of ribosomes when producing proteins. Thus, high production of one protein can lower the expression of others, since many ribosomes are bound on mRNAs of the former one and are not available for others. This effect is also known as "protein burden".
mRNA sequences can contain "slow" codons where ribosomes proceed much slower than on other parts of mRNA. These slow codons act as bottlenecks to protein synthesis, which can lead to ribosome queues on the mRNA molecules. We present a stochastic model for the traffic of ribosomes on many mRNAs competing for a finite pool of particles. Using realistic sequences of fast and slow codons, we show that ribosomal queues can effectively buffer the free ribosome pool, making it independent of fluctuations in mRNA-number and total amount of ribosomes. The effect can reduce the protein burden due to high expressions of a single gene. This mechanism works instantaneously and does not require explicit regulation of the ribosome pool.
Our results may have significant implications for cells' ability to respond independently to multiple demands on the ribosome pool.