New insights into the function of plant tannase with promiscuous acyltransferase activity

Abstract

SUMMARY Plant tannases (TAs) or tannin acyl hydrolases, a class of recently reported carboxylesterases in tannin‐rich plants, are involved in the degalloylation of two important groups of secondary metabolites: flavan‐3‐ol gallates and hydrolyzable tannins. In this paper, we have made new progress in studying the function of tea (Camellia sinensis) (Cs) TA—it is a hydrolase with promiscuous acyltransferase activity in vitro and in vivo and promotes the synthesis of simple galloyl glucoses and flavan‐3‐ol gallates in plants. We studied the functions of CsTA through enzyme analysis, protein mass spectrometry, and metabolic analysis of genetically modified plants. Firstly, CsTA was found to be not only a hydrolase but also an acyltransferase. In the two‐step catalytic reaction where CsTA hydrolyzes the galloylated compounds epigallocatechin‐3‐gallate or 1,2,3,4,6‐penta‐O‐galloyl‐β‐d‐glucose into their degalloylated forms, a long‐lived covalently bound Ser159‐linked galloyl–enzyme intermediate is also formed. Under nucleophilic attack, the galloyl group on the intermediate is transferred to the nucleophilic acyl acceptor (such as water, methanol, flavan‐3‐ols, and simple galloyl glucoses). Then, metabolic analysis suggested that transient overexpression of TAs in young strawberry (Fragaria × ananassa) fruits, young leaves of tea plants, and young leaves of Chinese bayberry (Myrica rubra) actually increased the total contents of simple galloyl glucoses and flavan‐3‐ol gallates. Overall, these findings provide new insights into the promiscuous acyltransferase activity of plant TA.

Deep learning and targeted metabolomics‐based monitoring of chewing insects in tea plants and screening defense compounds

“…A previously reported method was used to verify the function of CsHCTs in tea plants (Chen et al, 2023; Li et al, 2022). A suspension of Agrobacterium tumefaciens with CsHCT2 was injected into the third leaf of the tea plants, and an empty suspension of A. tumefaciens without the target gene was used as the control.…”

“…A previously described procedure (Chen et al, 2023; Li et al, 2022), with slight modifications, was used to obtain the third leaf of tea plants transiently overexpressing CsHCTs . Agrobacterium (GV3101 (pSoup‐19) chemically competent cell) transformed with the CsHCTs construct was grown in liquid LB medium and then resuspended in Agrobacterium suspension buffer containing 10 mM MES, 10 mM MgCl 2 , and 100 μM acetosyringone (As) to a final OD of 1.0.…”

2,4‐Dihydroxybenzoic Acid, a Novel SA Derivative, Controls Plant Immunity via UGT95B17‐Mediated Glucosylation: A Case Study in Camellia Sinensis

“…To further investigate the function of UGT95B17, we tried to increase the expression of UGT95B17 according to a previously established method. [ 16 ] The relative expression level of UGT95B17 was significantly up‐regulated in young leaves of tea plants compared to the control group (Figure 6F). Moreover, the content of SA in UGT95B17 over‐expressed tea leaves was increased by 2.22‐fold compared to that in the control leaves ( Figure F).…”

“…Transient Overexpression of UGT95B17 in Leaves of Tea Plants: A bud and two leaves of tea plants transiently overexpressing UGT95B17 were obtained using a previously described procedure with minor modifications. [16] Agrobacterium transformed with the UGT95B17 construct (GV3101 (pSoup-p19) Chemically Competent Cell) was grown in liquid LB medium and then resuspended to a final OD of 1.0 for injection. Agrobacterium carrying the empty pCAMBIA 1302 vector with eGFP was injected as a control.…”

A chromosome‐scale genome of Rhus chinensis Mill. provides new insights into plant–insect interaction and gallotannins biosynthesis

“…Gallotannins are the most important active chemical substance in CG (Tian et al., 2009; Zhu et al., 2009). HTs, which are classified into two primary categories, gallotannins, and ellagitannins, are naturally occurring compounds present in numerous genera such as Rhus , Vitis , Rubus , Quercus , Juglans , Acacia , Castanea , Lotus , Picea , Sapium , Schinopsis , Terminalia , Punica , Fragaria , Eucalyptus , and Camellia (Chen et al., 2023; Fraga‐Corral et al., 2021; Hwang et al., 2019; Katja et al., 2016; Ma et al., 2020; Muccilli et al., 2017; Ono et al., 2016; Ricci et al., 2017; Tahara et al., 2018). Gallotannins are composed of a polyol in the center and varying amounts of galloyl groups (Hwang et al., 2019; Ma et al., 2020; Xiang et al., 2007).…”