Study of light-induced MscL gating by EPR spectroscopy

Area of Science:

• Biochemistry
• Biophysics
• Structural Biology

Background:

• Investigating protein structure and function often relies on chemical modification and labeling.
• Homooligomeric proteins present challenges for selective residue labeling due to identical subunits.

Purpose of the Study:

• To develop a method for selectively labeling a defined number of subunits in a homopentameric mechanosensitive ion channel.
• To study initial conformational changes during channel gating.

Main Methods:

• Simultaneous labeling of channel subunits with a light-sensitive activator and a spin label.
• Utilizing electron paramagnetic resonance (EPR) spectroscopy to monitor structural changes.
• Controlled activation of the mechanosensitive channel of large conductance (MscL) into sub-open states.

Main Results:

• The developed method enabled controlled opening of MscL into distinct sub-open states.
• Increased light activation correlated with decreased intersubunit spin-spin interactions.
• Changes in intersubunit proximities were observed, indicating channel opening.

Conclusions:

• This method allows controlled activation of MscL into various open states using a noninvasive trigger.
• It facilitates the study of conformational changes associated with mechanosensation via spectroscopy.
• Paves the way for detailed spectroscopic investigations in mechanosensation research.