Cross‐compartment metabolic coupling enables flexible photoprotective mechanisms in the diatomPhaeodactylum tricornutum

• DOI: 10.1111/nph.15685
• Publication Date: 2019-01-13T11:24:02Z
• Authors: Jared T. Broddrick; Niu Du; Sarah R. Smith; Yoshinori Tsuji; Denis Jallet; Maxwell A. Ware; Graham Peers; Yusuke Matsuda; Chris L. Dupont; B. Greg Mitchell; Bernhard O. Palsson; Andrew E. Allen
• Keywords: Phaeodactylum tricornutum; Photorespiration; Metabolic network; Photoprotection; Metabolic pathway

Summary Photoacclimation consists of short‐ and long‐term strategies used by photosynthetic organisms to adapt dynamic light environments. Observable photophysiology changes resulting from these have been in coarse‐grained models predict light‐dependent growth rates. However, the contribution broader metabolic network, relevant species‐specific fitness, is not accounted for simple models. We incorporated experimental data with genome‐scale modeling characterize organism‐level, model diatom Phaeodactylum tricornutum . Oxygen evolution photon absorption rates were combined condition‐specific biomass compositions pathway usage cells acclimated four different intensities. Photorespiration, an ornithine‐glutamine shunt, branched‐chain amino acid metabolism hypothesized as primary intercompartment reductant shuttles mediating excess energy dissipation. Additionally, simulations suggested that carbon shunted through photorespiration recycled back chloroplast pyruvate, a mechanism distinct known organisms. Our results suggest flexible network P. tunes optimize transport between organelles, consuming needed. Characterization broadens our understanding partitioning this clade ecologically important producers.