Policing starter unit selection of the enterocin type II polyketide synthase by the type II thioesterase EncL

John A. Kalaitzis, Qian Cheng, Dario Meluzzi, Longkuan Xiang, Miho Izumikawa, Pieter C. Dorrestein, Bradley S. Moore*

*Corresponding author for this work

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Enterocin is an atypical type II polyketide synthase (PKS) product from the marine actinomycete 'Streptomyces maritimus'. The enterocin biosynthesis gene cluster (enc) codes for proteins involved in the assembly and attachment of the rare benzoate primer that initiates polyketide assembly with the addition of seven malonate molecules and culminates in a Favorskii-like rearrangement of the linear poly-β-ketone to give its distinctive non-aromatic, caged core structure. Fundamental to enterocin biosynthesis, which utilizes a single acyl carrier protein (ACP), EncC, for both priming with benzoate and elongating with malonate, involves maintaining the correct balance of acyl-EncC substrates for efficient polyketide assembly. Here, we report the characterization of EncL as a type II thioesterase that functions to edit starter unit (mis)priming of EncC. We performed a series of in vivo mutational studies, heterologous expression experiments, in vitro reconstitution studies, and Fourier-transform mass spectrometry-monitored competitive enzyme assays that together support the proposed selective hydrolase activity of EncL toward misprimed acetyl-ACP over benzoyl-ACP to facilitate benzoyl priming of the enterocin PKS complex. While this system resembles the R1128 PKS that also utilizes an editing thioesterase (ZhuC) to purge acetate molecules from its initiation module ACP in favor of alkylacyl groups, the enterocin system is distinct in its usage of a single ACP for both priming and elongating reactions with different substrates.

Original languageEnglish
Pages (from-to)6633-6638
Number of pages6
JournalBioorganic and Medicinal Chemistry
Volume19
Issue number22
DOIs
Publication statusPublished - 15 Nov 2011
Externally publishedYes

Keywords

  • Biosynthesis
  • Polyketide antibiotic
  • Streptomyces

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