Widening the landscape of transcriptional regulation of green algal photoprotection

Abstract

Availability of light and CO2, substrates of microalgae photosynthesis, is frequently far from optimal. Microalgae activate photoprotection under strong light, to prevent oxidative damage, and the CO2 Concentrating Mechanism (CCM) under low CO2, to raise intracellular CO2 levels. The two processes are interconnected; yet, the underlying transcriptional regulators remain largely unknown. Employing a large transcriptomic data compendium of Chlamydomonas reinhardtii’s responses to different light and carbon supply, we reconstruct a consensus genome-scale gene regulatory network from complementary inference approaches and use it to elucidate transcriptional regulators of photoprotection. We show that the CCM regulator LCR1 also controls photoprotection, and that QER7, a Squamosa Binding Protein, suppresses photoprotection- and CCM-gene expression under the control of the blue light photoreceptor Phototropin. By demonstrating the existence of regulatory hubs that channel light- and CO2-mediated signals into a common response, our study provides an accessible resource to dissect gene expression regulation in this microalga.

Proteomic characterization of a lutein-hyperaccumulating Chlamydomonas reinhardtii mutant reveals photoprotection-related factors as targets for increasing cellular carotenoid content

“…The regulation of C. reinhardtii qE-related proteins LHCSR1, LHCSR3, and PSBS, which are notably increased in Mut-5 (Fig. 3 E), has recently been a topic of avid investigation in C. reinhardtii photosynthesis research [ 80 , 99 – 102 ]. Under ambient conditions, the LHCSR and PSBS proteins are virtually undetectable [ 103 ].…”

Knocking Out Chloroplastic Aldolases/Rubisco Lysine Methyltransferase Enhances Biomass Accumulation in Nannochloropsis oceanica under High-Light Stress

“…to produce significant quantities of triacylglycerides and high-value products, including eicosapentaenoic acid, under various environmental conditions and at large scales, has attracted industrial interest [20]. Exceptional genetic tools, such as random insertional mutagenesis [21], gene overexpression [22], homologous recombination [23], RNAi-based gene knockdown [24], and Cas9-based gene knockout [25], have greatly facilitated mechanistic investigations for transcriptional regulation [26], the carbon concentrating mechanism [27], photosynthesis [28], phytohormone function [29], carbon partitioning [30], oil metabolism [31], etc. Therefore, Nannochloropsis spp.…”