Editors' ChoiceMicrobiology

Coming in From the Cold for a DesK Job

STKE  10 Apr 2001:
Vol. 2001, Issue 77, pp. tw6
DOI: 10.1126/stke.2001.77.tw6

In response to cold shock, Bacillus subtilis makes unsaturated fatty acids (UFAs) that become part of its lipid membrane to prevent changes in the physical characteristics of the lipids at low temperatures. Aguilar et al. identified a two-component signal transduction system, consisting of the cold-sensing kinase DesK and its response regulator DesR, that regulates the synthesis of UFAs. DesR bound to a dyad-symmetric element in the promoter of the Δ5-lipid desaturase (des) gene responsible for making UFAs, and overexpression of DesR correlated with increased amounts of Δ5-lipid desaturase activity. Further experiments revealed that the presence of UFAs led to decreased transcription from the Δ5-lipid desaturase promoter in gene reporter assays, suggesting that UFAs function in a negative feedback system to decrease des transcription. Thus, the range of a two-component histidine kinase-regulator system can be extended to include responses to cold temperature.

P. S. Aguilar, A. M. Hernandez-Arriaga, L. E. Cybulski, A. C. Erazo, D. de Mendoza, Molecular basis of thermosensing: A two-component signal transduction thermometer in Bacillus subtilis. EMBO J. 20, 1681-1691 (2001). [Abstract] [Full Text]