Bacterial Analogs to Cholesterol Affect Dimerization of Proteorhodopsin and Modulates Preferred Dimer Interface

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Hopanoids are bacterial sterol analogues crucial for survival under stress.
• Hopanoids exhibit structural diversity, impacting membrane properties and protein behavior.
• The role of hopanoids in bacterial membrane protein organization remains largely unexplored.

Purpose of the Study:

• To investigate the effects of two hopanoids, diploptene (DPT) and bacteriohopanetetrol (BHT), on proteorhodopsin (PR) oligomerization.
• To elucidate how hopanoid structure influences membrane protein organization and function.
• To understand the biophysical mechanisms by which hopanoids modulate membrane protein behavior.

Main Methods:

• Coarse-grained molecular dynamics simulations were employed.
• The study utilized a model membrane system composed of POPE and POPG lipids.
• The oligomerization of proteorhodopsin (PR) in the presence of DPT and BHT was characterized.

Main Results:

• Both DPT and BHT concentration-dependently tune membrane properties, indirectly affecting PR dimerization.
• BHT intercalates within the PR dimer interface, while DPT influences dimerization through interleaflet membrane packing.
• Distinct hopanoid structures lead to varied interactions with PR, affecting dimer interface plasticity.

Conclusions:

• Hopanoid structure directly correlates with the lateral organization of bacterial membrane proteins like PR.
• These findings offer insights into how bacterial hopanoids achieve sterol-like biophysical effects in cell membranes.
• Hopanoids play a significant role in modulating membrane protein behavior and function.