Biosynthesis of chlorophyll c in a dinoflagellate and heterologous production in planta
Robert E. Jinkerson, Daniel Poveda-Huertes, Elizabeth C. Cooney, Anna Cho, Rocio Ochoa‐Fernandez, Patrick J. Keeling, T. Xiang, Johan Andersen‐Ranberg
Abstract
Chlorophyll c is a key photosynthetic pigment that has been used historically to classify eukaryotic algae. Despite its importance in global photosynthetic productivity, the pathway for its biosynthesis has remained elusive. Here we define the CHLOROPHYLL C SYNTHASE ( CHLCS ) discovered through investigation of a dinoflagellate mutant deficient in chlorophyll c . CHLCSs are proteins with chlorophyll a / b binding and 2-oxoglutarate-Fe(II) dioxygenase (2OGD) domains found in peridinin-containing dinoflagellates; other chlorophyll c -containing algae utilize enzymes with only the 2OGD domain or an unknown synthase to produce chlorophyll c . 2OGD-containing synthases across dinoflagellate, diatom, cryptophyte, and haptophyte lineages form a monophyletic group, 8 members of which were also shown to produce chlorophyll c . Chlorophyll c 1 to c 2 ratios in marine algae are dictated in part by chlorophyll c synthases. CHLCS heterologously expressed in planta results in the accumulation of chlorophyll c 1 and c 2 , demonstrating a path to augment plant pigment composition with algal counterparts.