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Molecules. 2017 Feb 11;22(2). pii: E272. doi: 10.3390/molecules22020272.

Experimental Evidence and In Silico Identification of Tryptophan Decarboxylase in Citrus Genus.

Author information

1
Consiglio Nazionale delle Ricerche (CNR), Istituto di Biologia Agroambientale e Forestale (IBAF), via P. Castellino 111, 80131 Napoli, Italy. luigi.demasi@cnr.it.
2
Ministero dello Sviluppo Economico (MiSE), via Molise 2, 00187 Roma, Italy. dcastaldo@ssea.it.
3
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.
4
CNR, Istituto di Bioscienze e Biorisorse (IBBR), via G. Amendola 165/A, 70126 Bari, Italy. domenico.pignone@ibbr.cnr.it.
5
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.
6
CNR, Istituto di Scienze dell'Alimentazione (ISA), via Roma 64, 83100 Avellino, Italy. angelo.facchiano@isa.cnr.it.

Abstract

Plant tryptophan decarboxylase (TDC) converts tryptophan into tryptamine, precursor of indolealkylamine alkaloids. The recent finding of tryptamine metabolites in Citrus plants leads to hypothesize the existence of TDC activity in this genus. Here, we report for the first time that, in Citrus x limon seedlings, deuterium labeled tryptophan is decarboxylated into tryptamine, from which successively deuterated N,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 the Citrus genomes using as a probe the TDC sequence reported for the plant Catharanthus roseus. We analyzed the genomes of both Citrus clementina and Citrus 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 genus Citrus.

KEYWORDS:

Citrus clementina; Citrus genomes; Citrus sinensis; Citrus x limon; function prediction; tryptamine; tryptophan decarboxylase

PMID:
28208655
DOI:
10.3390/molecules22020272
[Indexed for MEDLINE]
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