Mass spectrometric characterization of a three-enzyme tandem reaction for assembly and modification of the novobiocin skeleton

Na Pi, Caren L. Freel Meyers, Michelle Pacholec, Christopher T. Walsh, Julie A. Leary

Research output: Contribution to journalArticle


The tripartite scaffold of the natural product antibiotic novobiocin is assembled by the tandem action of novobiocin ligase (NovL) and novobiocic acid noviosyl transferase (NovM). The noviosyl ring of the tripartite scaffold is further decorated by a methyltransferase (NovP) and a carbamoyltransferase (NovN), resulting in the formation of novobiocin. To facilitate kinetic evaluation of alternate substrate usage by NovL and NovM toward the creation of variant antibiotic scaffolds, an electrospray ionization/MS assay for obtaining kinetic measurements is presented for NovL and NovM separately, in each case with natural substrate and the 3-methyl-4-hydroxybenzoic acid analog. Additionally, assays of tandem two-enzyme (NovL/NovM) and three-enzyme (NovL/NovM/NovP) incubations were developed. The development of these assays allows for the direct detection of each intermediate followed by its utilization as substrate for the next enzyme, as well as the subsequent formation of final product as a function of time. This MS tandem assay is useful for optimization of conditions for chemoenzymatic generation of novobiocin and is also suitable for evaluation of competitive usage of variant substrate analogs by multiple enzymes. The studies presented here serve as a platform for the subsequent expansion of the repertoire of coumarin-based antibiotics.

Original languageEnglish (US)
Pages (from-to)10036-10041
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number27
StatePublished - Jul 6 2004
Externally publishedYes


ASJC Scopus subject areas

  • General

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