Transcriptional Regulation of Tetrapyrrole Biosynthesis in Arabidopsis thaliana

Abstract

Biosynthesis of chlorophyll (Chl) involves many enzymatic reactions that share several first steps for biosynthesis of other tetrapyrroles such as heme, siroheme, and phycobilins. Chl allows photosynthetic organisms to capture light energy for photosynthesis but with simultaneous threat of photooxidative damage to cells. To prevent photodamage by Chl and its highly photoreactive intermediates, photosynthetic organisms have developed multiple levels of regulatory mechanisms to coordinate tetrapyrrole biosynthesis (TPB) with the formation of photosynthetic and photoprotective systems and to fine-tune the metabolic flow with the varying needs of Chl and other tetrapyrroles under various developmental and environmental conditions. Among a wide range of regulatory mechanisms of TPB, this review summarizes transcriptional regulation of TPB genes during plant development, with focusing on several transcription factors characterized in Arabidopsis thaliana. Key TPB genes are tightly coexpressed with other photosynthesis-associated nuclear genes and are induced by light, oscillate in a diurnal and circadian manner, are coordinated with developmental and nutritional status, and are strongly downregulated in response to arrested chloroplast biogenesis. LONG HYPOCOTYL 5 and PHYTOCHROME-INTERACTING FACTORs, which are positive and negative transcription factors with a wide range of light signaling, respectively, target many TPB genes for light and circadian regulation. GOLDEN2-LIKE transcription factors directly regulate key TPB genes to fine-tune the formation of the photosynthetic apparatus with chloroplast functionality. Some transcription factors such as FAR-RED ELONGATED HYPOCOTYL3, REVEILLE1, and scarecrow-like transcription factors may directly regulate some specific TPB genes, whereas other factors such as GATA transcription factors are likely to regulate TPB genes in an indirect manner. Comprehensive transcriptional analyses of TPB genes and detailed characterization of key transcriptional regulators help us obtain a whole picture of transcriptional control of TPB in response to environmental and endogenous cues.

Beyond pathways: genetic dissection of tocopherol content in maize kernels by combining linkage and association analyses

“…The function of GRMZM5G888696 was further supported by a pleiotropic QTL that was detected in two independent RIL populations (ZHENG58/SK and DAN340/K22) (Tables S2 and S7). GRMZM2G024739 was significant for GT and TT, and its orthologue, CRY1, has been reported to regulate chlorophyll biosynthesis (Kobayashi and Masuda, 2016;McCormac and Terry, 2002;Stephenson and Terry, 2008). Furthermore, we found that natural variations in fatty acid pathway genes affect phenotypic variation in tocopherol content, which is supported by at least four points of evidence.…”

“…The function of GRMZM5G888696 was further supported by a pleiotropic QTL that was detected in two independent RIL populations (ZHENG58/SK and DAN340/K22) (Tables S2 and S7). GRMZM2G024739 was significant for GT and TT, and its orthologue, CRY1 , has been reported to regulate chlorophyll biosynthesis (Kobayashi and Masuda, ; McCormac and Terry, ; Stephenson and Terry, ).…”

“…All lines were self-pollinated, and kernels from the middle of at least three ears were employed to extract and measure tocopherols. The extraction procedures were adapted from previous studies (Chander et al, 2008;Kurilich and Juvik, 1999). Tocopherol quantification was performed via high-performance liquid chromatography (HPLC) .…”

Bilin-Dependent Photoacclimation in Chlamydomonas reinhardtii

“…Faulty regulation is potentially lethal due to release of photosensitizing intermediates such as protoporphyrin IX (PPIX) or Mg-protoporphyrin IX (Mg-PPIX) in the presence of oxygen and light (Rebeiz et al, 1990;Mochizuki et al, 2010;Busch and Montgomery, 2015). Heme and chlorophyll biosynthesis in plants and algae share a trunk pathway in which PPIX is derived from the amino acid glutamate (reviewed in Grossman et al, 2004;Tanaka and Tanaka, 2007;Kobayashi and Masuda, 2016). PPIX is the penultimate intermediate in both pathways, which diverge upon addition of either Fe 2+ for heme or Mg 2+ for chlorophyll ( Figure 1).…”

OUP accepted manuscript

“…Likewise, during development under either short day conditions or in continuous light, ASC and sGluTR correlated and peaked after two weeks. GluTR levels and activity are known to be low in darkgrown plants but to massively increase upon illumination and, inversely, to diminish when lightgrown plants are transferred to extended darkness (Kobayashi and Masuda 2016). The authors analyzed the distribution of GluTR between stroma and membrane fraction under such conditions.…”