Stochastic kinetics of ribosomes: Single motor properties and collective behavior

Garai, Ashok and Chowdhury, Debanjan and Chowdhury, Debashish and Ramakrishnan, TV (2009) Stochastic kinetics of ribosomes: Single motor properties and collective behavior. In: Physical Review E, 80 (1, Par).

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Abstract

Syntheses of protein molecules in a cell are carried out by ribosomes.A ribosome can be regarded as a molecular motor which utilizes the input chemical energy to move on a messenger RNA (mRNA) track that also serves as a template for the polymerization of the corresponding protein. The forward movement, however, is characterized by an alternating sequence of translocation and pause. Using a quantitative model, which captures the mechanochemical cycle of an individual ribosome, we derive an exact analytical expression for the distribution of its dwell times at the successive positions on the mRNA track. Inverse of the average dwell time satisfies a Michaelis-Menten-type'' equation and is consistent with the general formula for the average velocity of a molecular motor with an unbranched mechanochemical cycle. Extending this formula appropriately, we also derive the exact force-velocity relation for a ribosome. Often many ribosomes each synthesizes a copy of the same protein. We extend the model of a single ribosome by incorporating steric exclusion of different individuals on the same track. We draw the phase diagram of this model of ribosome traffic in three-dimensional spaces spanned by experimentally controllable parameters. We suggest new experimental tests of our theoretical predictions.

Item Type:	Journal Article
Publication:	Physical Review E
Publisher:	American physical society
Additional Information:	Copyright of this article belongs to America Physical Society.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	22 Dec 2009 07:24
Last Modified:	19 Sep 2010 05:41
URI:	http://eprints.iisc.ac.in/id/eprint/22436

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