title: A Picrinine N-Methyltransferase Belongs to a New Family of γ-Tocopherol-Like Methyltransferases Found in Medicinal Plants That Make Biologically Active Monoterpenoid Indole Alkaloids.
abstract: Members of the Apocynaceae plant family produce a large number of monoterpenoid indole alkaloids (MIAs) with different substitution patterns that are responsible for their various biological activities. A novel N-methyltransferase involved in the vindoline pathway in Catharanthus roseus showing distinct similarity to γ-tocopherol C-methyltransferases was used in a bioinformatic screen of transcriptomes from Vinca minor, Rauvolfia serpentina, and C. roseus to identify 10 γ-tocopherol-like N-methyltransferases from a large annotated transcriptome database of different MIA-producing plant species (www.phytometasyn.ca). The biochemical function of two members of this group cloned from V. minor (VmPiNMT) and R. serpentina (RsPiNMT) have been characterized by screening their biochemical activities against potential MIA substrates harvested from the leaf surfaces of MIA-accumulating plants. The approach was validated by identifying the MIA picrinine from leaf surfaces of Amsonia hubrichtii as a substrate of VmPiNMT and RsPiNMT. Recombinant proteins were shown to have high substrate specificity and affinity for picrinine, converting it to N-methylpicrinine (ervincine). Developmental studies with V. minor and R. serpentina showed that RsPiNMT and VmPiNMT gene expression and biochemical activities were highest in younger leaf tissues. The assembly of at least 150 known N-methylated MIAs within members of the Apocynaceae family may have occurred as a result of the evolution of the γ-tocopherol-like N-methyltransferase family from γ-tocopherol methyltransferases.
authors: Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada L2S 3A1.
authors: Dylan
authors: D
authors: Levac
authors: Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada L2S 3A1.
authors: Paulo
authors: P
authors: Cázares
authors: Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada L2S 3A1.
authors: Fang
authors: F
authors: Yu
authors: Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada L2S 3A1 vdeluca@brocku.ca.
authors: Vincenzo
authors: 0000-0001-8925-9382
authors: V
authors: De Luca
mesh_terms: D029062:Apocynaceae / Q000201:enzymology / Q000235:genetics; D055162:Biocatalysis; D002851:Chromatography, High Pressure Liquid; D057225:Data Mining; D019992:Databases as Topic; D018506:Gene Expression Regulation, Plant; D026121:Indole Alkaloids / Q000378:metabolism*; D008780:Methyltransferases / Q000378:metabolism*; D005810:Multigene Family; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D010946:Plants, Medicinal / Q000201:enzymology*; D021382:Protein Sorting Signals; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D046948:Secologanin Tryptamine Alkaloids / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D026121:Indole Alkaloids; D010936:Plant Extracts; D010940:Plant Proteins; D021382:Protein Sorting Signals; D012333:RNA, Messenger; D011994:Recombinant Proteins; D046948:Secologanin Tryptamine Alkaloids; C528220:picrinine; D008780:Methyltransferases; C047259:gamma-tocopherol methyltransferase