Surface charge dynamics in photosynthetic membranes and the structural consequences

Area of Science:

• Plant biology
• Photosynthesis research
• Membrane biophysics

Background:

• Plant photosynthetic membranes form grana structures crucial for energy conversion.
• The molecular mechanisms driving grana stacking are not fully understood.

Purpose of the Study:

• To investigate the role of electrostatic (F_el) and van der Waals (F_vdWaals) forces in grana stacking.
• To analyze the impact of these forces on photosystem II (PSII)-light harvesting complex II (LHCII) supercomplex stability and organization.

Main Methods:

• Evaluation of the physicochemical balance between attractive and repulsive forces.
• Force balance analysis extended to lateral interactions within PSII-LHCII supercomplexes.
• Assessment of electrostatic force dynamics, including changes due to protein phosphorylation.

Main Results:

• The balance of attractive and repulsive forces fully accounts for grana stacking.
• Supercomplex stability is highly sensitive to dynamic changes in electrostatic forces.
• Phosphorylation-induced charge changes significantly alter electrostatic forces, affecting supercomplex stability.
• Electrostatic force changes have differential effects on vertical stacking and lateral organization.

Conclusions:

• A physicochemical force balance model accurately explains grana stacking.
• Dynamic modulation of electrostatic forces provides biological control over photosynthetic membrane structure.
• This control mechanism influences both grana stacking and lateral organization within membranes, impacting energy conversion efficiency.