Synergistic Interactions between Carotene Ring Hydroxylases Drive Lutein Formation in Plant Carotenoid Biosynthesis

Quinlan, Rena F.; Shumskaya, Maria; Bradbury, Louis Mt; Beltrán, Jesús; Ma, Chunhui; Kennelly, Edward J.; Wurtzel, Eleanore T.

doi:10.1104/pp.112.198556

Cited by 93 publications

(80 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…S4). The relatively low level of ER:LUT1 transorganellar complementation may be attributable to poor interaction of the enzyme with the ER cytochrome P450 reductase or the inability of ER-localized LUT1 to form complexes with other plastid-resident carotenoid biosynthetic enzymes (15,16).…”

Section: Demonstration Of Transorganellar Complementation With Additimentioning

confidence: 99%

Transorganellar complementation redefines the biochemical continuity of endoplasmic reticulum and chloroplasts

Mehrshahi¹,

Stefano

Andaloro³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

136

115

View full text Add to dashboard Cite

Tocopherols are nonpolar compounds synthesized and localized in plastids but whose genetic elimination specifically impacts fatty acid desaturation in the endoplasmic reticulum (ER), suggesting a direct interaction with ER-resident enzymes. To functionally probe for such interactions, we developed transorganellar complementation, where mutated pathway activities in one organelle are experimentally tested for substrate accessibility and complementation by active enzymes retargeted to a companion organelle. Mutations disrupting three plastid-resident activities in tocopherol and carotenoid synthesis were complemented from the ER in this fashion, demonstrating transorganellar access to at least seven nonpolar, plastid envelope-localized substrates from the lumen of the ER, likely through plastid:ER membrane interaction domains. The ability of enzymes in either organelle to access shared, nonpolar plastid metabolite pools redefines our understanding of the biochemical continuity of the ER and chloroplast with profound implications for the integration and regulation of organelle-spanning pathways that synthesize nonpolar metabolites in plants.n addition to meeting cellular energy needs through photosynthesis, chloroplasts are centers of anabolic metabolism that contain complete biosynthetic pathways (e.g., for de novo synthesis of fatty acids, amino acids, tocopherols, and carotenoids) and participate in numerous pathways that span multiple subcellular compartments (e.g., for synthesis of membrane lipids, monoterpenes, diterpenes, and photorespiration). Such metabolism requires exchange of a multitude of polar and nonpolar metabolites with the extraplastidic environment and consistent with this, proteomic and bioinformatic analysis of the chloroplast envelope identified 102 transporter candidates (Dataset S1). Sixty-six have recognized functions as ion or metabolite transporters, but only one transports nonpolar metabolites. This apparent paucity of nonpolar metabolite transporters in the envelope, despite the large numbers of nonpolar metabolites synthesized by plastids, highlights a significant gap in our understanding of plant metabolism.Tocochromanols are one well-studied group of nonpolar compounds synthesized and localized in plastids that include the biosynthetically related tocopherols, tocotrienols, and plastochromanol-8 (PC8) (Fig. 1). Tocochromanol biosynthesis has been fully elucidated, null mutants with well-defined biochemical phenotypes are available for each reaction, and with the exception of p-hydroxyphenylpyruvate dioxygenase, all biosynthetic activities localize to the plastid inner envelope where synthesis occurs (1, 2). Because tocochromanols are only present in chloroplast membranes (1, 3), it was assumed that their functions would be restricted to this organelle; however, many tocopheroldeficient mutant phenotypes are, instead, consistent with impacts on extraplastidic processes. These include alterations in membrane lipids, formation of secretory pathway-derived vesicles, cell-wall developmen...

show abstract

Section: Demonstration Of Transorganellar Complementation With Additimentioning

confidence: 99%

Transorganellar complementation redefines the biochemical continuity of endoplasmic reticulum and chloroplasts

Mehrshahi¹,

Stefano

Andaloro³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

136

115

View full text Add to dashboard Cite

show abstract

“…Carotenoid metabolons (enzyme complexes) are predicted to exist on the basis of high molecular weight complexes containing PSY or other carotenoid enzymes (Maudinas et al, 1977;Camara et al, 1982;Kreuz et al, 1982;Al-Babili et al, 1996;Bonk et al, 1997;Lopez et al, 2008). A recent study showed that the capacity for enzymes to interact was associated with enhanced carotenoid pathway activity (Quinlan et al, 2012). Metabolon-associated enzymes could facilitate substrate channeling, as has been suggested by the absence of carotenoid pathway intermediates, except in cases where the pathway is artificially blocked (Wurtzel, 2004).…”

Section: Open Questions On Metabolon Organization and Dynamicsmentioning

confidence: 99%

Plastid Localization of the Key Carotenoid Enzyme Phytoene Synthase Is Altered by Isozyme, Allelic Variation, and Activity

et al. 2012

Self Cite

View full text Add to dashboard Cite

Plant carotenoids have unique physiological roles related to specific plastid suborganellar locations. Carotenoid metabolic engineering could enhance plant adaptation to climate change and improve food security and nutritional value. However, lack of fundamental knowledge on carotenoid pathway localization limits targeted engineering. Phytoene synthase (PSY), a major rate-controlling carotenoid enzyme, is represented by multiple isozymes residing at unknown plastid sites. In maize (Zea mays), the three isozymes were transiently expressed and found either in plastoglobuli or in stroma and thylakoid membranes. PSY1, with one to two residue modifications of naturally occurring functional variants, exhibited altered localization, associated with distorted plastid shape and formation of a fibril phenotype. Mutating the active site of the enzyme reversed this phenotype. Discovery of differential PSY locations, linked with activity and isozyme type, advances the engineering potential for modifying carotenoid biosynthesis.

show abstract

“…A phylogenetic analysis with the deduced amino acid sequence (616 amino acids) confirmed its identity as carrot CYP97A3 ( Figure 5A). This was concluded from the high sequence identity to several cytochrome P450 enzymes, which were functionally confirmed as b-ring-specific a-carotene hydroxylases, e.g., from tomato (Sl-CYP97A29, 76% identity; Stigliani et al, 2011), rice (Os-CYP97A4, 69% identity; Quinlan et al, 2012), and Arabidopsis CYP97A3 (71% identity; alignment in Supplemental Figure 6). In contrast, the sequence exhibited only 41% identity to e-ring-specific carotene hydroxylases, including carrot CYP97C1, and branched-off separately in phylogenetic analysis, excluding that the sequence obtained represented an additional CYP97C1 copy ( Figure 5A).…”

Section: Cloning Of Cyp97a3 From White Carrotsmentioning

confidence: 99%

Carotene Hydroxylase Activity Determines the Levels of Both α-Carotene and Total Carotenoids in Orange Carrots

et al. 2014

View full text Add to dashboard Cite

The typically intense carotenoid accumulation in cultivated orange-rooted carrots (Daucus carota) is determined by a high protein abundance of the rate-limiting enzyme for carotenoid biosynthesis, phytoene synthase (PSY), as compared with white-rooted cultivars. However, in contrast to other carotenoid accumulating systems, orange carrots are characterized by unusually high levels of a-carotene in addition to b-carotene. We found similarly increased a-carotene levels in leaves of orange carrots compared with white-rooted cultivars. This has also been observed in the Arabidopsis thaliana lut5 mutant carrying a defective carotene hydroxylase CYP97A3 gene. In fact, overexpression of CYP97A3 in orange carrots restored leaf carotenoid patterns almost to those found in white-rooted cultivars and strongly reduced a-carotene levels in the roots. Unexpectedly, this was accompanied by a 30 to 50% reduction in total root carotenoids and correlated with reduced PSY protein levels while PSY expression was unchanged. This suggests a negative feedback emerging from carotenoid metabolites determining PSY protein levels and, thus, total carotenoid flux. Furthermore, we identified a deficient CYP97A3 allele containing a frame-shift insertion in orange carrots. Association mapping analysis using a large carrot population revealed a significant association of this polymorphism with both a-carotene content and the a-/b-carotene ratio and explained a large proportion of the observed variation in carrots.

show abstract

Synergistic Interactions between Carotene Ring Hydroxylases Drive Lutein Formation in Plant Carotenoid Biosynthesis

Cited by 93 publications

References 36 publications

Transorganellar complementation redefines the biochemical continuity of endoplasmic reticulum and chloroplasts

Transorganellar complementation redefines the biochemical continuity of endoplasmic reticulum and chloroplasts

Plastid Localization of the Key Carotenoid Enzyme Phytoene Synthase Is Altered by Isozyme, Allelic Variation, and Activity

Carotene Hydroxylase Activity Determines the Levels of Both α-Carotene and Total Carotenoids in Orange Carrots

Contact Info

Product

Resources

About