Phototropin connects blue light perception to starch metabolism in green algae
Yizhong Yuan, Anthony A. Iannetta, Minjae Kim, Patric W. Sadecki, Marius Arend, Angeliki Tsichla, M. Águila Ruiz‐Sola, Georgios Kepesidis, Denis Falconet, Emmanuel Thévenon, Marianne Tardif, Sabine Brugière, Yohann Couté, Jean-Philippe Kleman, И. А. Сизова, Marion Schilling, Juliette Jouhet, Peter Hegemann, Yonghua Li‐Beisson, Zoran Nikoloski, Olivier Bastien, Leslie M. Hicks, Dimitris Petroutsos
Abstract
into carbohydrates used for growth or storage. The main storage carbohydrate in green algae is starch, which accumulates during the day and is broken down at night to meet cellular energy demands. The signaling role of light quality in the regulation of starch accumulation remains unexplored. Here, we identify PHOTOTROPIN-MEDIATED SIGNALING KINASE 1 (PMSK1) as a key regulator of starch metabolism in Chlamydomonas reinhardtii. In its phosphorylated form (PMSK1-P), it activates GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE (GAP1), promoting starch biosynthesis. We show that blue light, perceived by PHOTOTROPIN, induces PMSK1 dephosphorylation that in turn represses GAP1 mRNA levels and reduces starch accumulation. These findings reveal a previously uncharacterized blue light-mediated signaling pathway that advances our understanding of photoreceptor-controlled carbon metabolism in microalgae.