Dynamics and Structural Responses to Cis-Trans Isomerization in Bacterial Lipid Bilayers

Area of Science:

• Biochemistry
• Cell Biology
• Computational Biology

Background:

• Cells adapt to environmental changes using mechanisms like altering cell membrane fluidity.
• Gram-negative bacteria utilize fatty acid cis-trans isomerization to adjust membrane composition in response to temperature shifts.
• This isomerization impacts membrane rigidity and lipid acyl tail fluidity, maintaining homeostasis.

Purpose of the Study:

• To investigate the impact of fatty acid cis-trans isomerization on membrane properties and dynamics.
• To model these effects in *Pseudomonas putida* using molecular dynamics (MD) simulations.
• To quantify the variations in membrane properties between all-cis and all-trans configurations.

Main Methods:

• Employed molecular dynamics (MD) simulations for a membrane model of *Pseudomonas putida*.
• Simulated transitions between all-cis and all-trans fatty acid configurations.
• Analyzed changes in membrane thickness, lipid diffusion, and unsaturation site accessibility.

Main Results:

• Fatty acid cis-trans isomerization significantly alters membrane thickness and lipid diffusion rates.
• Unsaturation sites in cis fatty acids exhibit a higher probability of residing at the membrane surface compared to trans fatty acids.
• This positional difference may affect enzymatic interactions and protein accessibility.

Conclusions:

• Cis-trans isomerization is a rapid, biosynthesis-independent mechanism for bacterial adaptation to environmental stress.
• The study quantifies the biophysical consequences of this isomerization on membrane properties.
• Findings suggest implications for enzyme activity and peripheral membrane protein function.