A Chemoenzymatic Approach to Investigate Cytochrome P450 Cross-Linking in Glycopeptide Antibiotic Biosynthesis

Y. T.Candace Ho, Yongwei Zhao, Julien Tailhades, Max J. Cryle

Research output: Chapter in Book/Report/Conference proceedingChapter (Book)Otherpeer-review


Glycopeptide antibiotics (GPAs) are important and medically relevant peptide natural products. In the context of antimicrobial resistance (AMR), understanding and manipulating GPA biosynthesis is essential to discover new bioactive derivatives of these peptides. Among all the enzymatic steps in GPA biosynthesis, the most complex occurs during the maturation (cross-linking) of the peptide aglycone. This is achieved-while the peptide remains attached to the nonribosomal peptide synthetase (NRPS) machinery-through the action of a cytochrome P450 (CYP450 or Oxy)-mediated cyclization cascade. There is great interest in understanding the formation of the cross-links between the aromatic side chains in GPAs as this process leads to the cup-shaped aglycone, which is itself a requirement for antibiotic activity. In this regard, the use of in vitro experiments is crucial to study this process. To address the process of peptide cyclization during GPA biosynthesis, a series of peptide substrates and different Oxy enzymes are required. In this chapter, we describe a practical and efficient route for the synthesis of peptidyl-CoAs, the expression of proteins/enzymes involved in the in vitro cyclization assay, the loading of the PCP with peptidyl-CoAs, an optimized CYP450-mediated cyclization cascade and assay workup followed by mass spectrometry (MS) characterization. This in vitro assay affords high conversion to cyclic peptides and demonstrates the tolerance of the P450s for novel GPA precursor peptide substrates.

Original languageEnglish
Title of host publicationNon-Ribosomal Peptide Biosynthesis and Engineering
EditorsMichael Burkart, Fumihiro Ishikawa
Place of PublicationNew York NY USA
PublisherHumana Press
Number of pages20
ISBN (Electronic)9781071632147
ISBN (Print)9781071632130, 9781071632161
Publication statusPublished - 2023

Publication series

NameMethods in Molecular Biology
PublisherHumana Press
ISSN (Print)1064-3745
ISSN (Electronic)1940-6029


  • Bioconjugation
  • Coenzyme A
  • Cytochrome P450
  • Glycopeptide antibiotics
  • Nonribosomal peptide synthetase
  • Solid-phase peptide synthesis

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