High-Throughput Localization of Proteins with Predicted Photosynthetic Function in the Green Alga Chlamydomonas reinhardtii

Abstract

Photosynthesis in modern plants is hindered by inefficiencies such as photorespiration, which is caused by the unintended oxygenase activity of the key photosynthetic enzyme Rubisco. Some organisms, such as the green alga Chlamydomonas reinhardtii, have evolved carbon concentrating mechanisms (CCMs) in order to mitigate this activity and increase their photosynthetic capacity. The introduction of CCMs into plants lacking these mechanisms presents an open avenue for increases in biofuel and crop yield. However, a greater understanding of the genes and proteins involved in photosynthesis is needed before the engineering of a complete, fully functional CCM into crop plants will be feasible. In the present study, we attempt to fluorescently tag and localize 97 candidate proteins with predicted photosynthetic function in Chlamydomonas, using a high-throughput pipeline designed by the Jonikas lab. We successfully localized 26 of these proteins and assigned them to one of 9 localization categories. 7 of these categories represent sub-chloroplast designations, encompassing 22 proteins. We also found 12 proteins, some poorly characterized, to be present within the pyrenoid, the site of algal CCM activity. These results will inform a more complete understanding of photosynthesis and direct the selection of candidate photosynthetic proteins for future studies.