The heme cofactor is used in several bacterial transcription factors as the allosteric effector site. In these gas-sensing proteins, a gas such as CO or NO binds to the heme following reduction of the heme iron. Upon reduction, a ligand switch occurs priming the iron for gas binding. These proteins are only active and able to bind DNA in the gas-bound state. While much is known about the changes at the heme, it is unclear how gas binding activates these proteins. Site directed spin labeling is a valuable strategy for studying the conformational and dynamical changes in these transcription factors. Spin labels positioned at key points in CO-sensing CooA report on local motion, revealing differences among the domains that may be relevant for protein function.

Conformational and dynamical changes in gas-sensing transcription factors

246th National Meeting (2013)

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