Title: A mechanistic model of the cellular resource allocation strategy in bacteria

Speaker: Dr. Anjan Roy, ICTP, Trieste

Abstract: Bacterial growth requires protein synthesis. It is carried out by cellular machines called ribosomes which polymerize amino acids into proteins. However, being made up of protein sub-units themselves the ribosomes not only have to synthesize other proteins, like the metabolic proteins converting environmental nutrients into amino acids, but also their own sub-units. Therefore, a bacterial cell is faced with this interesting trade-off of how much of its ribosomes should it allocate to producing more ribosomes as opposed to producing other proteins, so as to optimize the utilization of the machines and the nutrient resources. We present a simple, mechanistic model which demonstrates this trade-off, and show that there exists an optimal allocation parameter which maximizes the growth rate of the cell. Moreover, bacteria must dynamically adapt their growth to changes in the environment. We show how the bacterial cell uses a simple feedback mechanism to achieve this, by dynamically driving this allocation parameter towards the optimal value for different environments. The resultant model is consequently capable of explaining various experimental results pertaining to the effect of nutrient, antibiotic and other such perturbations under one unified framework.