Quieting a noisy antenna reproduces photosynthetic light harvesting spectra

Abstract

Photosynthesis is remarkable, achieving near unity light harvesting quantum efficiency in spite of dynamic light conditions and noisy physiological environment. Under these adverse conditions, it remains unknown whether there exists a fundamental organizing principle that gives rise to robust photosynthetic light harvesting. Here, we present a noise-canceling network model that relates noisy physiological conditions, power conversion efficiency, and the resulting absorption spectrum of photosynthetic organisms. Taking external light conditions in three distinct niches - full solar exposure, light filtered by oxygenic phototrophs, and under sea water - we derive optimal absorption characteristics for efficient solar power conversion. We show how light harvesting antennae can be finely tuned to maximize power conversion efficiency by minimizing excitation noise, thus providing a unified theoretical basis for the experimentally observed wavelength dependence of light absorption in green plants, purple bacteria, and green sulfur bacteria.