Extended Data Fig. 7 | Analysis of putative endoproteolytic propeptide
removal in AbLS. a, Sequence alignment of AbLS with characterized serine
carboxypeptidases and SCPL acyltransferases known to possess (AtS C T,
AsSCPL1, TaCBP2) or lack (AtSMT, yPRC1) proteolytically-removed internal
propeptide linkers (red). Putative N-terminal signal peptides are indicated in
bold; disulfide bonds are indicated in blue. AtS C T, Arabidopsis thaliana
sinapoylglucose:choline sinapoyltransferase; AtS M T, A. thaliana
sinapoylglucose:malate sinapoyltransferase; AbLS, Atropa belladonna littorine
synthase; AsSCPL1, Avena strigosa avenacin synthase; TaCBP2, Triticum
aestivum carboxypeptidase 2; yPRC1, yeast carboxypeptidase Y. b, d, Crystal
structure of TaCBP2 (PDB: 1WHT) in cartoon (b) and surface (d) representation
showing disulfide bonds (yellow) and internal propeptide removal sites.
c, e, Homology model of AbLS based on the crystal structure of TaCBP2 in
cartoon (c) and surface (e) representation showing N-terminal signal peptide
(red, bottom right in c), disulfide bonds (yellow), and putative internal
propeptide (red, top/middle), which appears to block active site access. Note
that surface views in d and e are rotated 90° towards the viewer.