The swimming behaviour of Halobacterium cells controlled by a small network of interacting proteins
Halobacterium salinarum cells respond to light, nutrients, and noxious chemicals by swimming to those places
of their natural habitat that provide the best living conditions available at the moment.
Sensory receptors feed into a core signal processing network composed of 11 cytoplasmic proteins
which mediates signal integration, adaptation and motor response. Because the network is small
and many molecular details are known, mechanistic questions related to receptor activation,
functional cross-talk of receptors, or the biophysical chemistry of signal processing can be
addressed at the single cell level.
A kinetic model of the signal processing network quantitatively predicts the
cellular response to complex patterns of light stimulation, and the spontaneous
behaviour of the cell. This model is continually refined to improve our systems level
understanding and to incorporate more mechanistic details.
Sensing and response in Halobacterium is the only example where the structure
and dynamics of a signaling network has been studied in-depth within
the archaeal branch of life. Comparison with bacteria and eukaryotes may
contribute to our understanding of how molecular signaling systems evolve.
Review article:
Marwan, W., and D. Oesterhelt. 1999. Biochemical mechanisms of a simple behavioural response.
Chemie in unserer Zeit 33:140-151
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Fig. 1 Simplified scheme of the core biochemical reactions that control the response
of Halobacterium salinarum to light. Note that for simplicity, only one of many different receptors is shown.
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