Atomic force microscopy differentiates discrete size distributions between membrane protein containing and empty...

Area of Science:

• Biophysics
• Biochemistry
• Materials Science

Background:

• Nanolipoprotein particles (NLPs) are crucial for studying membrane proteins.
• Understanding NLP self-assembly with embedded proteins is key for structural biology.

Purpose of the Study:

• To investigate the effect of bacteriorhodopsin (bR) incorporation on NLP assembly using atomic force microscopy (AFM).
• To analyze NLP size distribution and identify subpopulations during self-assembly.

Main Methods:

• Atomic Force Microscopy (AFM) for imaging and height analysis of NLPs.
• Ion Mobility Spectrometry (IMS) for size distribution analysis.
• Streptavidin binding assay to confirm bR incorporation.

Main Results:

• Two distinct NLP populations were observed: bR-NLPs and empty-NLPs.
• bR-NLPs showed an average height increase of 1.0 nm compared to empty-NLPs.
• NLP size distribution revealed subpopulations, with bR presence shifting distribution towards larger particles.

Conclusions:

• Membrane protein incorporation, specifically bR, influences NLP self-assembly dynamics.
• Larger NLPs exhibit a higher probability of containing membrane proteins.
• This suggests membrane proteins actively modulate the NLP assembly mechanism.