Gatekeeping versus promiscuity in the early stages of the andrimid biosynthetic assembly line

Nathan A. Magarvey, Pascal D. Fortin, Paul M. Thomas, Neil L. Kelleher, Christopher T. Walsh

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

The antibiotic andrimid, a nanomolar inhibitor of bacterial acetyl coenzyme A carboxylase, is generated on an unusual polyketide/nonribosomal peptide enzyme assembly line in that all thiolation (T) domains/small-molecule building stations are on separate proteins. In addition, a transglutaminase homologue is used to condense andrimid building blocks together on the andrimid assembly line. The first two modules of the andrimid assembly line yields an octatrienoyl-β-Phe-thioester tethered to the AdmI T domain, with amide bond formation carried out by a free-standing transglutaminase homologue AdmF. Analysis of the aminomutase AdmH reveals its specific conversion from L-Phe to (S)-β-Phe, which in turn is activated by AdmJ and ATP to form (S)-β-Phe-aminoacyl-AMP. AdmJ then transfers the (S)-β-Phe moiety to one of the free-standing T domains, AdmI, but not AdmA, which instead gets loaded with an octatrienoyl group by other enzymes. AdmF, the amide synthase, will accept a variety of acyl groups in place of the octatrienoyl donor if presented on either AdmA or AdmI. AdmF will also use either stereoisomer of phenylalanine or β-Phe when presented on AdmA and AdmI, but not when placed on noncognate T domains. Further, we show the polyketide synthase proteins responsible for the polyunsaturated acyl cap can be bypassed in vitro with N-acetylcysteamine as a low-molecular-weight acyl donor to AdmF and also in vivo in an Escherichia coli strain bearing the andrimid biosynthetic gene cluster with a knockout in admA.

Original languageEnglish (US)
Pages (from-to)542-554
Number of pages13
JournalACS chemical biology
Volume3
Issue number9
DOIs
StatePublished - Sep 19 2008

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine

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