Following Oxygen

Photo: Changes within HemAT

When oxygen binds to the sensor
domain, the protein conformation
in the vicinity of the sensor
domain changes; © RUB

The research team investigated the conformational changes within the protein HemAT. Via a signal transduction chain, this protein sends a command to the flagellar motor which controls the movement direction.

The signal transduction chain starts with binding of oxygen to HemAT’s heme domain, which is also known from haemoglobin in the red blood cells and is called the sensor domain of HemAT. Oxygen binding leads to a conformational change in the sensor domain. This in turn provokes several further conformational changes within HemAT that finally affect the signalling domain of the protein. The signalling domain then transmits the information about a rise in oxygen concentration to other proteins within the cell. These proteins forward the message to the motor of the flagellum. The research team investigated how the information travels from the sensor domain of HemAT to its signalling domain.

For that purpose, El-Mashtoly used the time-resolved ultraviolet resonance Raman spectroscopic facilities in the Picobiology Institute in Japan. This method provides, for instance, structural information about the conformation of the protein and hydrogen bonding interactions on a nanosecond to microsecond time scale. The results suggest that the conformational change in the sensor domain, in example, the heme structure, induces the displacement of two protein helices within HemAT. This displacement affects another helix which is continuous with the structure of the signalling domain. Due to a series of conformational changes, the information about oxygen binding thus reaches the signalling domain of the protein.; Source: Ruhr University Bochum