This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Synonyms: capsaicinoids biosynthesis, hot pepper biosynthesis
|Superclasses:||Biosynthesis → Secondary Metabolites Biosynthesis → Nitrogen-Containing Secondary Compounds Biosynthesis → Alkaloids Biosynthesis|
Expected Taxonomic Range: Solanaceae
The pungency in food flavored with chili or hot peppers comes from phenolic alkaloids called capsaicinoids. These are exclusively produced in fruits of plants belonging to the Capsicum genus. A quarter of the world population consumes hot peppers in some form daily [Prasad06]. Structurally capsaicinoids have a common aromatic moiety, vanillylamine and variable lengths of short chain fatty acids that also differ in the degree of saturation [Curry99].
The accumulation of capsaicinoids is strictly correlated with developmental stages of the fruit and usually spans the ripening stages after fruit size increase has ceased [Sukrasno93]. The capsaicinoids are localized in the epidermal cells of the fruit placenta [Aluru03]. Pungency differs considerably in species ranging from very hot to sweet peppers and has a positive relation with amount of critical capsaicinoids biosynthetic gene expression [Aluru03], capsaicin and dihydrocapsaicin are the most common types, other naturally occurring capsaicinoids include nordihydrocapsacin, homodihydrocapsaicin, homocapsaicin, norcapsaicin, and nornorcapsaicin differing in fatty acid chain length (n=7-10) [Curry99].
The pathway leading to capsaicin formation has two distinct arms, one that contributes the fatty acid moiety, usually formed via CoA derivatives of an amino acid like valine and the other is an aromatic component that is derived from the phenylpropanoid biosynthesis [Sukrasno93]. The initial steps of phenylpropanoid biosynthesis is similar to ones in other plants that give rise to a number of metabolic intermediates, but the steps from ferulate to vanillylamine production is unique to Capsicum.
Vanilloid receptor (VR1) is responsible for the perception of these compounds; birds the main dispersal agent of Capsicum seeds lack a functional VR1. In humans, the VR1 is involved in the pain sensing pathways [Caterina00] and capsaicins have been used as analgesics and are an effective treatment against nerve pain and arthritis [Ribbers01].
Aluru03: Aluru MR, Mazourek M, Landry LG, Curry J, Jahn M, O'Connell MA (2003). "Differential expression of fatty acid synthase genes, Acl, Fat and Kas, in Capsicum fruit." J Exp Bot 54(388);1655-64. PMID: 12810854
Caterina00: Caterina MJ, Leffler A, Malmberg AB, Martin WJ, Trafton J, Petersen-Zeitz KR, Koltzenburg M, Basbaum AI, Julius D (2000). "Impaired nociception and pain sensation in mice lacking the capsaicin receptor." Science 288(5464);306-13. PMID: 10764638
Curry99: Curry, J, Aluru, M, Mendoza, M, Nevarez, J, Melendrez, M, O' Connell, M. A (1999). "Transcripts for posssible capsaicinoid biosynthetic genes are differentially accumulated in pungent and non-pungent Capsicum." Plant Science, 148, 47-57.
Prasad06: Prasad BC, Kumar V, Gururaj HB, Parimalan R, Giridhar P, Ravishankar GA (2006). "Characterization of capsaicin synthase and identification of its gene (csy1) for pungency factor capsaicin in pepper (Capsicum sp.)." Proc Natl Acad Sci U S A 103(36);13315-20. PMID: 16938870
Stewart05a: Stewart C, Kang BC, Liu K, Mazourek M, Moore SL, Yoo EY, Kim BD, Paran I, Jahn MM (2005). "The Pun1 gene for pungency in pepper encodes a putative acyltransferase." Plant J 42(5);675-88. PMID: 15918882
Grienenberger09: Grienenberger E, Besseau S, Geoffroy P, Debayle D, Heintz D, Lapierre C, Pollet B, Heitz T, Legrand M (2009). "A BAHD acyltransferase is expressed in the tapetum of Arabidopsis anthers and is involved in the synthesis of hydroxycinnamoyl spermidines." Plant J 58(2);246-59. PMID: 19077165
Ibdah03: Ibdah M, Zhang XH, Schmidt J, Vogt T (2003). "A novel Mg(2+)-dependent O-methyltransferase in the phenylpropanoid metabolism of Mesembryanthemum crystallinum." J Biol Chem 278(45);43961-72. PMID: 12941960
Kai08: Kai K, Mizutani M, Kawamura N, Yamamoto R, Tamai M, Yamaguchi H, Sakata K, Shimizu B (2008). "Scopoletin is biosynthesized via ortho-hydroxylation of feruloyl CoA by a 2-oxoglutarate-dependent dioxygenase in Arabidopsis thaliana." Plant J 55(6);989-99. PMID: 18547395
Kopycki08: Kopycki JG, Rauh D, Chumanevich AA, Neumann P, Vogt T, Stubbs MT (2008). "Biochemical and structural analysis of substrate promiscuity in plant Mg2+-dependent O-methyltransferases." J Mol Biol 378(1);154-64. PMID: 18342334
Lepelley07: Lepelley, M, Simkina, A, Cheminadea, G, Cailleta, V, Tremillon, N, McCarthy, J (2007). "Chlorogenic acid synthesis in coffee: An analysis of CGA content and real-time RT-PCR expression of HCT, HQT, C3H1, and CCoAOMT1 genes during grain development in C. canephora." Plant Science, 172, 978-996.
Masai02: Masai E, Harada K, Peng X, Kitayama H, Katayama Y, Fukuda M (2002). "Cloning and characterization of the ferulic acid catabolic genes of Sphingomonas paucimobilis SYK-6." Appl Environ Microbiol 68(9);4416-24. PMID: 12200295
Rubio06: Rubio S, Larson TR, Gonzalez-Guzman M, Alejandro S, Graham IA, Serrano R, Rodriguez PL (2006). "An Arabidopsis mutant impaired in coenzyme A biosynthesis is sugar dependent for seedling establishment." Plant Physiol 140(3);830-43. PMID: 16415216
Wils13: Wils CR, Brandt W, Manke K, Vogt T (2013). "A single amino acid determines position specificity of an Arabidopsis thaliana CCoAOMT-like O-methyltransferase." FEBS Lett 587(6);683-9. PMID: 23416302
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