Modeling incoherent exciton transport between chlorosome tubes

Area of Science:

• Biophysics
• Photosynthesis research
• Bacterial light-harvesting complexes

Background:

• Chlorosomes function as efficient antennae in green (non-sulfur) bacteria.
• Exciton transport governs ultrafast energy transfer in natural light-harvesting systems.
• Exciton delocalization over many molecules in chlorosomes necessitates studying large model systems.

Purpose of the Study:

• To investigate exciton dynamics in a large-scale chlorosome model.
• To analyze energy transfer timescales between chlorosome walls.
• To understand in vivo exciton transport within chlorosomes.

Main Methods:

• Utilized a Frenkel exciton Hamiltonian for a three coaxial tube chlorosome model.
• Employed all-atom molecular dynamics simulations.
• Applied the time-domain Förster resonant energy transfer (FRET) method.

Main Results:

• Calculated population transfer rate between neighboring chlorosome walls at approximately 2.3 ps-1.
• Demonstrated that transfer timescales are largely independent of initial quantum states.
• Validated the model's ability to describe exciton dynamics in large systems.

Conclusions:

• Incoherent transfer between chlorosome walls occurs on picosecond timescales.
• The studied chlorosome model accurately reflects in vivo exciton delocalization and transport.
• Findings contribute to understanding efficient light capture in photosynthetic bacteria.