Cloning and characterization of a serotonin N-acetyltransferase from a gymnosperm, loblolly pine (Pinus taeda)

Serotonin N‐acetyltransferase (SNAT) is the penultimate enzyme in melatonin biosynthesis in both animals and plants. SNAT catalyzes serotonin into N‐acetylserotonin, an immediate precursor for melatonin biosynthesis by N‐acetylserotonin methyltransferase (ASMT). We cloned the SNAT gene from a gymnos...

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Bibliographic Details
Published in:Journal of pineal research 2014-10, Vol.57 (3), p.348-355
Main Authors: Park, Sangkyu, Byeon, Yeong, Lee, Hyoung Yool, Kim, Young-Soon, Ahn, Taeho, Back, Kyoungwhan
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Arylalkylamine N-Acetyltransferase - chemistry
Arylalkylamine N-Acetyltransferase - genetics
Arylalkylamine N-Acetyltransferase - isolation & purification
Base Sequence
Cloning, Molecular
DNA Primers
DNA, Plant
loblolly pine
melatonin
Phylogeny
Pinus - enzymology
Pinus - genetics
Pinus taeda
Polymerase Chain Reaction
Sequence Homology, Amino Acid
serotonin N-acetyltransferase
subcellular location
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Summary:Serotonin N‐acetyltransferase (SNAT) is the penultimate enzyme in melatonin biosynthesis in both animals and plants. SNAT catalyzes serotonin into N‐acetylserotonin, an immediate precursor for melatonin biosynthesis by N‐acetylserotonin methyltransferase (ASMT). We cloned the SNAT gene from a gymnosperm loblolly pine (Pinus teada). The loblolly pine SNAT (PtSNAT) gene encodes 255 amino acids harboring a transit sequence with 67 amino acids and shows 67% amino acid identity with rice SNAT when comparing the mature polypeptide regions. Purified recombinant PtSNAT showed peak activity at 55°C with the Km (428 μm) and Vmax (3.9 nmol/min/mg protein) values. As predicted, PtSNAT localized to chloroplasts. The SNAT mRNA was constitutively expressed in all tissues, including leaf, bud, flower, and pinecone, whereas the corresponding protein was detected only in leaf. In accordance with the exclusive SNAT protein expression in leaf, melatonin was detected only in leaf at 0.45 ng per gram fresh weight. Sequence and phylogenetic analysis indicated that the gymnosperm PtSNAT had high homology with SNATs from all plant phyla (even with cyanobacteria), and formed a clade separated from the angiosperm SNATs, suggestive of direct gene transfer from cyanobacteria via endosymbiosis.
ISSN:0742-3098
1600-079X
DOI:10.1111/jpi.12174