HemAT is a heme-based O2 sensor protein from Bacillus subtilis that acts as a signal transducer responsible for aerotaxis. FTIR and time-resolved step-scan (TRS2)-FTIR spectroscopies have been employed to gain insight into the structure and dynamics of the sensor domain and full length HemAT-CO adducts. The FTIR spectra of the CO-bound T95A, L92A, L92, L92V and Y70F mutants of full length HemAT demonstrate that Y70 is crucial for the discrimination of CO and that the presence of L92 is necessary to maintain the hydrogen bonding network between the heme-bound ligand and the distal residues. Mutations near the proximal heme site (K115A, R125A, Y133F, E172A, Q173A) have also been designed to explore possible communication pathways for intramolecular signal transduction. The (TRS2)-FTIR (td=ns-ms) approach has enabled us to measure the rate of CO rebinding and monitor structural perturbations induced by the photodissociation of CO from the wild type and mutant HemAT-CO adducts.

Structural properties and dynamics of the oxygen sensor protein HemAT as revealed by FTIR and time-resolved step scan FTIR spectroscopies

243rd National Meeting (2012)

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