%0 Journal Article
%T Metabolic Regulation of a Bacterial Cell System with Emphasis on Escherichia coli Metabolism
%A Kazuyuki Shimizu
%J ISRN Biochemistry
%D 2013
%R 10.1155/2013/645983
%X It is quite important to understand the overall metabolic regulation mechanism of bacterial cells such as Escherichia coli from both science (such as biochemistry) and engineering (such as metabolic engineering) points of view. Here, an attempt was made to clarify the overall metabolic regulation mechanism by focusing on the roles of global regulators which detect the culture or growth condition and manipulate a set of metabolic pathways by modulating the related gene expressions. For this, it was considered how the cell responds to a variety of culture environments such as carbon (catabolite regulation), nitrogen, and phosphate limitations, as well as the effects of oxygen level, pH (acid shock), temperature (heat shock), and nutrient starvation. 1. Introduction Although living organisms may have been created somehow with the formation of a compartmentalized autocatalytic cycles with the appearance of ribonucleic acid-based or protein-based enzymes gaining complexity, evolved by adapting to the environment on earth, and improved in their effectiveness and robustness [1], it is still not certain that evolution can solve all the mystery of highly efficient, robust, and well-organized cell systems. It might be true that evolution has played some important roles for the improvement of cell¡¯s function and robustness to the changes in the environment, but this may not be all that can explain the cell¡¯s complexity with efficient function. In the living organisms, metabolic network, defined as the set and topology of metabolic biochemical reactions within a cell, plays an essential role for the cell to survive, where it is under organized control. In living organisms or cells, thousands of different biochemical reactions as well as transport processes are linked together to break down organic compounds to generate energy and to synthesize macromolecular compounds for cell synthesis. Note that the set of enzyme reactions is not static as illustrated in the biochemistry text book, but the set itself changes dynamically in response to the changes in the growth environment and the cell¡¯s state. Similarly, complex signaling networks interconvert signals or stimuli that are important for cellular function and interactions with the environment. This implies the transfer of information in signal transduction pathways and cascades designed to maximize efficiency and cellular responses. It may be of importance to understand the evolution of metabolism and signalings for understanding the adaptation processes of cellular life and the emergence of higher levels of
%U http://www.hindawi.com/journals/isrn.biochemistry/2013/645983/