An Asymmetry-to-Symmetry Switch in Signal Transmission by the Histidine Kinase Receptor for TMAO

作者：Moore Jason O; Hendrickson Wayne A^*

来源：Structure, 2012, 20(4): 729-741.

DOI：10.1016/j.str.2012.02.021

The osmoregulator trimethylamine-N-oxide (TMAO), commonplace in aquatic organisms, is used as the terminal electron acceptor for respiration in many bacterial species. The TMAO reductase (Tor) pathway for respiratory catalysis is controlled by a receptor system that comprises the TMAO-binding protein TorT, the sensor histidine kinase TorS, and the response regulator TorR. Here we study the TorS/TorT sensor system to gain mechanistic insight into signaling by histidine kinase receptors. We determined crystal structures for complexes of TorS sensor domains with apo TorT and with TorT (TMAO); we characterized TorS sensor associations with TorT in solution; we analyzed the thermodynamics of TMAO binding to TorT-TorS complexes; and we analyzed in vivo responses to TMAO through the TorT/TorS/TorR system to test structure-inspired hypotheses. TorS-TorT(apo) is an asymmetric 2:2 complex that binds IMAO with negative cooperativity to form a symmetric active kinase.

• 出版日期2012-4-4