Structure of the stress-related LHCSR1 complex determined by an integrated computational strategy

Ingrid Guarnetti Prandi,Vladislav Sláma,Lorenzo Cupellini,Benedetta Mennucci,Cristina Pecorilla

doi:10.1038/s42003-022-03083-8

Ingrid Guarnetti Prandi, Vladislav Sláma + Show 3 more

Open Access

https://doi.org/10.1038/s42003-022-03083-8

Copy DOI

Journal: Communications Biology	Publication Date: Feb 17, 2022
Citations: 8	License type: open-access

Affiliation: Tuscia University, University of Pisa

Abstract

Light-harvesting complexes (LHCs) are pigment-protein complexes whose main function is to capture sunlight and transfer the energy to reaction centers of photosystems. In response to varying light conditions, LH complexes also play photoregulation and photoprotection roles. In algae and mosses, a sub-family of LHCs, light-harvesting complex stress-related (LHCSR), is responsible for photoprotective quenching. Despite their functional and evolutionary importance, no direct structural information on LHCSRs is available that can explain their unique properties. In this work, we propose a structural model of LHCSR1 from the moss P. patens, obtained through an integrated computational strategy that combines homology modeling, molecular dynamics, and multiscale quantum chemical calculations. The model is validated by reproducing the spectral properties of LHCSR1. Our model reveals the structural specificity of LHCSR1, as compared with the CP29 LH complex, and poses the basis for understanding photoprotective quenching in mosses.

Highlights

Light-harvesting complexes (LHCs) are pigment-protein complexes whose main function is to capture sunlight and transfer the energy to reaction centers of photosystems
LHCII has a slightly higher amino acid sequence similarity, CP29 was chosen as a template due to the loop length in the lumenal region, which matches LHCSR1
From the analysis reported in the previous section, it clearly appears that our simulated structure of LHCSR1 correctly reproduces the measured spectra including the small differences with respect to CP29

Summary

Introduction

Light-harvesting complexes (LHCs) are pigment-protein complexes whose main function is to capture sunlight and transfer the energy to reaction centers of photosystems. A sub-family of LHCs, light-harvesting complex stress-related (LHCSR), is responsible for photoprotective quenching. Despite their functional and evolutionary importance, no direct structural information on LHCSRs is available that can explain their unique properties. Algae express the so-called light-harvesting complex stress-related (LHCSR) proteins[5], which are responsible for quenching the excess energy as part of the NPQ mechanism.[6]. It seems that LHCSR proteins can directly sense pH changes in the thylakoid lumen and activate the quenching process at low pH7,8. We highlight important differences in the mutual orientation of a strongly coupled Chl cluster, that reflect in the spectral properties of LHCSR1

Methods

Results

Conclusion