Membrane Thickness Cue for Cold Sensing in a Bacterium

Thermosensors are ubiquitous integral membrane proteins found in all kinds of life. They are involved in many physiological roles, including membrane remodeling, chemotaxis, touch, and pain [ 1–3], but, the mechanism by which their transmembrane (TM) domains transmit temperature signals is largely u...

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Bibliographic Details
Published in:Current biology 2010-09, Vol.20 (17), p.1539-1544
Main Authors: Cybulski, Larisa E., Martín, Mariana, Mansilla, María C., Fernández, Ariel, de Mendoza, Diego
Format: Article
Language:English
Subjects:
Adaptations
Amino Acid Sequence
Bacillus subtilis
Bacillus subtilis - physiology
Bacterial Proteins - chemistry
Bacterial Proteins - physiology
Cell Membrane
Cold Temperature
Histidine Kinase
Membrane Proteins - chemistry
Membrane Proteins - physiology
Molecular Sequence Data
Phosphorylation
Point Mutation
Protein Kinases - chemistry
Protein Kinases - physiology
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Summary:Thermosensors are ubiquitous integral membrane proteins found in all kinds of life. They are involved in many physiological roles, including membrane remodeling, chemotaxis, touch, and pain [ 1–3], but, the mechanism by which their transmembrane (TM) domains transmit temperature signals is largely unknown. The histidine kinase DesK from Bacillus subtilis is the paradigmatic example of a membrane-bound thermosensor suited to remodel membrane fluidity when the temperature drops below ∼30°C [ 1, 4] providing, thus, a tractable system for investigating the mechanism of TM-mediated input-output control of thermal adaptation. Here we show that the multimembrane-spanning domain from DesK can be simplified into a chimerical single-membrane-spanning minimal sensor (MS) that fully retains, in vivo and in vitro, the sensing properties of the parental system. The MS N terminus contains three hydrophilic amino acids near the lipid-water interface creating an instability hot spot. Mutational analysis of this boundary-sensitive beacon revealed that membrane thickness controls the signaling state of the sensor by dictating the hydration level of the metastable hydrophilic spot. Guided by these results we biochemically demonstrated that the MS signal transmission activity is sensitive to bilayer thickness. Membrane thickness could be a general cue for sensing temperature in many organisms. ► The bacterial DesK thermosensor perceives cold through its transmembrane segments ► The polytopic DesK domain was simplified to a functional monotopic minimal sensor ► Membrane thickness controls the signaling state of the minimal sensor
ISSN:0960-9822
1879-0445
DOI:10.1016/j.cub.2010.06.074