Fig. 2: Characterization of SobAS1.
a, Phylogenetic analysis of candidate S. officinalis OSCs. The maximum-likelihood tree was generated using an amino acid alignment of putative OSCs in S. officinalis and previously characterized OSCs from other plant species (listed in Supplementary Table 6). Bootstrap values less than 80% are shown beside each node. The scale bar indicates the number of amino acid substitutions per site. Common enzyme products produced by each clade are labeled on the right. SobAS1, characterized in this work as a β-amyrin (1) synthase is highlighted in purple. The three other S. officinalis OSCs identified in this study are shown in bold. b, Transient expression of SobAS1 in N. benthamiana leaves. GC–MS total ion chromatograms (TICs) of leaf extracts coexpressing AstHMGR and SobAS1, along with a control (leaf expressing only AstHMGR) and a commercial standard of β-amyrin (1), are shown. Mass spectra for leaf extracts expressing SobAS1 and commercial β-amyrin standard are also given. c, Activity of SobAS1 in converting 2,3-oxidosqualene to β-amyrin (1).
