DocumentCode :
892393
Title :
System-level analysis of tryptophan regulation in Escherichia coli -- performance under starved and well-fed conditions
Author :
Chaudhary, N. ; Bhartiya, S. ; Venkatesh, K.V.
Author_Institution :
Dept. of Chem. Eng., IIT Bombay, Mumbai
Volume :
1
Issue :
3
fYear :
2007
fDate :
5/1/2007 12:00:00 AM
Firstpage :
181
Lastpage :
189
Abstract :
Biological systems respond appropriately to a variety of environments thus representing complex systems with rich physiological behaviour. Quantitative models can be used to identify the design components that result in the system complexity. In this work, the tryptophan system of Escherichia coli that synthesises tryptophan internally when faced with starvation in a rapid manner and shuts off the synthesis sluggishly when the cells are exposed to a medium replete with tryptophan has been discussed. The evolved regulatory design is capable of providing such an asymmetric response that represents an appropriate behaviour to ensure survival. The tryptophan system uses three distinct regulatory mechanisms namely genetic regulation, transcriptional attenuation and enzyme inhibition to achieve its goals. It has been shown that genetic repression and attenuation are the only active regulatory mechanisms during moderate and severe starvation. However, as the degree of starvation increases, repression is relieved prior to attenuation. The analysis also shows that enzyme inhibition does not play a role under severe starvation and plays a marginal role in increasing the rate of repression when the cells are exposed to well-fed conditions. Finally, we use tools from linear systems theory to rationalise the above observations based on the poles and zeros of an approximated linear system
Keywords :
cellular biophysics; microorganisms; Escherichia coli; approximated linear system; evolved regulatory design; physiological behaviour; regulatory mechanisms; starved conditions; tryptophan regulation; well-fed conditions;
fLanguage :
English
Journal_Title :
Systems Biology, IET
Publisher :
iet
ISSN :
1751-8849
Type :
jour
Filename :
4216753
Link To Document :
بازگشت