Identification and functional application of a new malonyltransferase NbMaT1 towards diverse aromatic glycosides from Nicotiana benthamiana

Abstract

Recently, owing to the important pharmaceutical properties of malonylated glycosides, their chemoenzymatic synthesis using malonyltransferase has received significant attention. In the present study, a new malonyltransferase, NbMaT1, was identified from Nicotiana benthamiana. Extensive enzymatic assays revealed its significant substrate tolerance based on HPLC-UV and HR-MS analyses.Moreover, 16 of the tested glycosides including flavone glycosides, flavonol glycosides, dihydroflavone glycosides, isoflavone glycosides, coumarin glycosides, and phenylethyl chromone glycosides with various sugar moieties (such as glucose, xylose, and galactose) substituted at different positions of their skeleton could be accepted by NbMaT1 to conduct the corresponding malonylation. Among these, enzymatic malonylation of phenylethyl chromone glycosides as well as xylosides and galactosides has rarely been reported earlier. Furthermore, one-pot synthesis using the known malonyl-CoA synthetase MatB and NbMaT1 as well as an unnatural fusion protein MatB-NbMaT1 was designed, which allowed malonic acid to be directly used in the malonylation reaction without the addition of expensive malonyl-CoA. Moreover, a remarkably improved conversion rate was observed for all the tested substrates, with both commercial and industrial application values. The malonylated product of the bioactive flavonoid diglycoside icariin was prepared and NMR spectroscopy revealed that the malonyl group was specifically transferred onto the 6-OH group of the glucose moiety.NbMaT1 was expected to be a universal and effective tool for chemoenzymatic synthesis of diverse bioactive-malonylated glycoside derivatives for drug discovery.

The decoration of specialized metabolites influences stylar development

“…Based on our current results, we infer that NaMaT1 is a malonyl-CoA:DTG malonyltransferase, which may catalyze three consecutive malonylation steps, as reported for Dm3MaT2, which catalyzes consecutive dimalonyl transfers to anthocyanin ( Suzuki et al, 2004 ). Notably, two characterized MaTs in the Nicotiana genus, NbMaT1 and NtMaT1, accept aromatic glycosides as substrate ( Taguchi et al, 2005 ; Liu et al, 2017 ). Phylogenic and protein identity analysis showed that NbMaT1 and NtMaT1 share the highest sequence similarity with NaMaT2 and NaMaT3, about 90%, whereas the identity with NaMaT1 is 80% ( Figure 2A and Figure 2—figure supplement 1B ).…”

Identification of α-Glucosidase Inhibitors from Leaf Extract of Pepper (Capsicum spp.) through Metabolomic Analysis

“…The isomers might have resulted from different glycosylation positions of the flavones, or malonylation could have occurred at various positions of the glucose or apiosyl. The 7-O position of the flavones and 6"-position glucose has been reported as the most frequent site of glycosylation and acylation, respectively [62,63]. For example, formononetin glucoside malonate isomers were found to show two acylation points on the sugar group identified as 7-O-β-D-glucoside 6"-O-malonate and 7-O-β-D-glucoside 4"-O-malonate [64].…”