TY - JOUR
T1 - Peptide macrocyclization by a bifunctional endoprotease
AU - Bernath-Levin, Kalia
AU - Nelson, C.
AU - Elliott, A.G.
AU - Jayasena, A.S.
AU - Millar, Harvey
AU - Craik, D.J.
AU - Mylne, Josh
PY - 2015/5
Y1 - 2015/5
N2 - © 2015 Elsevier Ltd. All rights reserved. Proteases usually cleave peptides, but under some conditions, they can ligate them. Seeds of the common sunflower contain the 14-residue, backbone-macrocyclic peptide sunflower trypsin inhibitor 1 (SFTI-1) whose maturation from its precursor has a genetic requirement for asparaginyl endopeptidase (AEP). To provide more direct evidence, we developed an in situ assay and used 18O-water to demonstrate that SFTI-1 is excised and simultaneously macrocyclized from its linear precursor. The reaction is inefficient in situ, but a newfound breakdown pathway can mask this inefficiency by reducing the internal disulfide bridge of any acyclic-SFTI to thiols before degrading it. To confirm AEP can directly perform the excision/ligation, we produced several recombinant plant AEPs in E. coli, and one from jack bean could catalyze both a typical cleavage reaction and cleavage-dependent, intramolecular transpeptidation to create SFTI-1. We propose that the evolution of ligating endoproteases enables plants like sunflower and jack bean to stabilize bioactive peptides.
AB - © 2015 Elsevier Ltd. All rights reserved. Proteases usually cleave peptides, but under some conditions, they can ligate them. Seeds of the common sunflower contain the 14-residue, backbone-macrocyclic peptide sunflower trypsin inhibitor 1 (SFTI-1) whose maturation from its precursor has a genetic requirement for asparaginyl endopeptidase (AEP). To provide more direct evidence, we developed an in situ assay and used 18O-water to demonstrate that SFTI-1 is excised and simultaneously macrocyclized from its linear precursor. The reaction is inefficient in situ, but a newfound breakdown pathway can mask this inefficiency by reducing the internal disulfide bridge of any acyclic-SFTI to thiols before degrading it. To confirm AEP can directly perform the excision/ligation, we produced several recombinant plant AEPs in E. coli, and one from jack bean could catalyze both a typical cleavage reaction and cleavage-dependent, intramolecular transpeptidation to create SFTI-1. We propose that the evolution of ligating endoproteases enables plants like sunflower and jack bean to stabilize bioactive peptides.
U2 - 10.1016/j.chembiol.2015.04.010
DO - 10.1016/j.chembiol.2015.04.010
M3 - Article
C2 - 25960260
SN - 1074-5521
VL - 22
SP - 571
EP - 582
JO - Chemistry and Biology
JF - Chemistry and Biology
IS - 5
ER -