Sensory transduction network of E. coli

Abstract

The genome of Escherichia coli K12 encodes at least 6 classes of sensor proteins: 30 histidine protein kinases, 5 methyl-accepting chemotaxis proteins, 23 membrane components of the sugar:phosphotransferase system (PTS), 29 proteins with diguanylate cyclase and/or c-di-GMP-specific phosphodiesterase activity and two predicted serine/threonine protein kinases. The full signal transduction network additionally includes 32 response regulators, numerous chemotaxis proteins, PTS components, adenylate cyclase, CRP, and uncharacterized c-di-GMP-responsive components. Bacterial response to environmental signals can occur on several levels: the level of individual genes and proteins (changes in gene expression, post-translational regulation), the whole-cell level (chemotaxis), and the multicellular level (biofilm formation). All signal transduction systems are energy-dependent but their energy expenditure is miniscule compared to that of the processes they regulate. A better understanding of the signal transduction mechanisms and integration of these mechanisms into the metabolic pathway model of the E. coli cell will remain major challenges for systems biology. © 2009 Springer Netherlands.