第1025回生物科学セミナー

Alternating access in ion-coupled and ABC transporters. A spin labeling EPR perspective

Dr. Hassane Mchaourab(Vanderbilt University Medical Center)

2015年02月20日(金)    10:00-11:00  理学部3号館303号室   

My laboratory uses spin labeling and electron paramagnetic resonance
(EPR) spectroscopy to define conformational rearrangements underlying the function of a broad spectrum of proteins. Specific examples include alternating access in multidrug and neurotransmitter transporters and the response of calcium-calmodulin dependent protein kinase to calcium signals, its activation and the structural basis of conformational memory. The main tool is Double Electron-Electron Resonance (DEER) spectroscopy for long range distance measurements between spin label pairs. The average distances from DEER yield the amplitude of protein motion. Analysis of the distance distribution can reveal equilibria between multiple intermediates in a native-like environment in the absence of conformational selectivity imposed by the crystal lattice. In this seminar, I will illustrate the use of the tools of EPR spectroscopy to define the proton-activated conformational switch of the multidrug antiporter LmrP, to uncover asymmetric conformations of the ABC heterodimeric transporter BrmCD, and to test models of LeuT conformational cycle.