Chlorophyll-Induced\nLamellar to Nonlamellar Phase\nTransitions and Dynamical Heterogeneity in Plant Thylakoid Membranes

Chlorophyll a (CLA) pigments and thylakoid membranes\nare crucial\ncomponents of plants for photosynthesis. To understand the effect\nof CLA on the structure and dynamics of thylakoid membranes, coarse-grained\nmolecular dynamics (CG MD) simulations of thylakoid membranes are\nperformed by varying the numbers of CLA at 293 K using MARTINI-2 force\nfields. The membrane undergoes a lamellar to nonlamellar phase transition\nabove a critical concentration of CLA. The CLAs dynamically form aggregates\nof different orders and preferentially fetch the least unsaturated\nnonbilayer-forming lipids around them, resulting in a nonlamellar\nphase with fused regions. These fused regions cause a structural arrest\nof CLA and lipids, inducing dynamic heterogeneity manifested by non-Gaussian\nparameters and van Hove correlation functions. The lamellar to nonlamellar\nphase transition of the membrane is associated with a drastic reduction\nin correlation length of the immobile CLA and lipids governed by the\nfused topology. Such insights into CLA-induced structural transitions\nin thylakoid membranes are pertinent for understanding nonphotochemical\nquenching mechanisms and hold promise for designing future artificial\nphotosynthetic materials and applications in photodynamic therapy.