title: Experimental Evidence and In Silico Identification of Tryptophan Decarboxylase in Citrus Genus.
abstract: Plant tryptophan decarboxylase (TDC) converts tryptophan into tryptamine, precursor of indolealkylamine alkaloids. The recent finding of tryptamine metabolites inCitrusplants leads to hypothesize the existence of TDC activity in this genus. Here, we report for the first time that, inCitrusxlimonseedlings, deuterium labeled tryptophan is decarboxylated into tryptamine, from which successively deuteratedN,N,N-trimethyltryptamine is formed. These results give an evidence of the occurrence of the TDC activity and the successive methylation pathway of the tryptamine produced from the tryptophan decarboxylation. In addition, with the aim to identify the genetic basis for the presence of TDC, we carried out a sequence similarity search for TDC in theCitrusgenomes using as a probe the TDC sequence reported for the plantCatharanthus roseus. We analyzed the genomes of bothCitrus clementinaandCitrus sinensis, available in public database, and identified putative protein sequences of aromatic l-amino acid decarboxylase. Similarly, 42 aromatic l-amino acid decarboxylase sequences from 23 plant species were extracted from public databases. Potential sequence signatures for functional TDC were then identified. With this research, we propose for the first time a putative protein sequence for TDC in the genusCitrus.
authors.affiliation: Consiglio Nazionale delle Ricerche (CNR), Istituto di Biologia Agroambientale e Forestale (IBAF), via P. Castellino 111, 80131 Napoli, Italy. luigi.demasi@cnr.it.
authors.forename: Luigi
authors.initials: L
authors.lastname: De Masi
authors.affiliation: Ministero dello Sviluppo Economico (MiSE), via Molise 2, 00187 Roma, Italy. dcastaldo@ssea.it.|Stazione Sperimentale per le Industrie delle Essenze e dei Derivati dagli Agrumi (SSEA), Azienda Speciale della Camera di Commercio di Reggio Calabria, via Gen. Tommasini 2, 89125 Reggio Calabria, Italy. dcastaldo@ssea.it.
authors.forename: Domenico
authors.initials: D
authors.lastname: Castaldo
authors.affiliation: CNR, Istituto di Bioscienze e Biorisorse (IBBR), via G. Amendola 165/A, 70126 Bari, Italy. domenico.pignone@ibbr.cnr.it.
authors.forename: Domenico
authors.initials: D
authors.lastname: Pignone
authors.affiliation: Dipartimento di Biochimica, Biofisica e Patologia Generale, Università degli Studi della Campania "Luigi Vanvitelli", via L. De Crecchio 7, 80138 Napoli, Italy. luigi.servillo@unina2.it.
authors.forename: Luigi
authors.initials: L
authors.lastname: Servillo
authors.affiliation: CNR, Istituto di Scienze dell'Alimentazione (ISA), via Roma 64, 83100 Avellino, Italy. angelo.facchiano@isa.cnr.it.
authors.forename: Angelo
authors.initials: A
authors.lastname: Facchiano
mesh_terms: D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000235:genetics* / Q000378:metabolism; D002957:Citrus / Q000201:enzymology* / Q000235:genetics*; D019295:Computational Biology / Q000379:methods; D004789:Enzyme Activation; D020869:Gene Expression Profiling; D058977:Molecular Sequence Annotation; D010802:Phylogeny; D036226:Seedlings / Q000235:genetics / Q000378:metabolism; D014363:Tryptamines / Q000378:metabolism
chemical_list: D014363:Tryptamines; C030820:tryptamine; D001142:Aromatic-L-Amino-Acid Decarboxylases
keywords: Citrus clementina; Citrus genomes; Citrus sinensis; Citrus x limon; function prediction; tryptamine; tryptophan decarboxylase