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The soluble guanylate cyclase CYG 12 is required for the acclimation to hypoxia and trophic regimes in Chlamydomonas reinhardtii
Author(s) -
Düner Melis,
Lambertz Jan,
Mügge Carolin,
Hemschemeier Anja
Publication year - 2018
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13779
Subject(s) - chlamydomonas reinhardtii , biology , photosynthesis , acclimatization , microbiology and biotechnology , mixotroph , nitric oxide , biochemistry , botany , gene , heterotroph , bacteria , genetics , mutant , endocrinology
Summary Oxygenic phototrophs frequently encounter environmental conditions that result in intracellular energy crises. Growth of the unicellular green alga Chlamydomonas reinhardtii in hypoxia in the light depends on acclimatory responses of which the induction of photosynthetic cyclic electron flow is essential. The microalga cannot grow in the absence of molecular oxygen (O 2 ) in the dark, although it possesses an elaborate fermentation metabolism. Not much is known about how the microalga senses and signals the lack of O 2 or about its survival strategies during energy crises. Recently, nitric oxide ( NO ) has emerged to be required for the acclimation of C . reinhardtii to hypoxia. In this study, we show that the soluble guanylate cyclase ( sGC ) CYG 12, a homologue of animal NO sensors, is also involved in this response. CYG 12 is an active sGC , and post‐transcriptional down‐regulation of the CYG 12 gene impairs hypoxic growth and gene expression in C . reinhardtii . However, it also results in a disturbed photosynthetic apparatus under standard growth conditions and the inability to grow heterotrophically. Transcriptome profiles indicate that the mis‐expression of CYG 12 results in a perturbation of responses that, in the wild‐type, maintain the cellular energy budget. We suggest that CYG 12 is required for the proper operation of the photosynthetic apparatus which, in turn, is essential for survival in hypoxia and darkness.