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Reductase of Mutanobactin Synthetase Triggers Sequential C-C Macrocyclization, C-S Bond Formation, and C-C Bond

Min Wang1,2,3, Zhoujie Xie1, Shoubin Tang2

  • 1State Key Laboratory of Microbial Resources & CAS Key Laboratory of Microbial Physiological and Metabolic Engineering , Institute of Microbiology, Chinese Academy of Sciences , Beijing 100101 , China.

Organic Letters
|January 10, 2020
PubMed

Insights

Mutanobactins, lipopeptides from Streptococcus mutans, are formed via spontaneous macrocyclization. Intermediates released as aldehydes enable C-C bond formation, leading to diverse congeners through C-S bond formation and C-C cleavage.

Area of Science:

  • Biochemistry
  • Microbiology
  • Organic Chemistry

Background:

  • Mutanobactins (MUBs) are lipopeptides produced by Streptococcus mutans, a key bacterium in dental caries.
  • MUBs and their congeners feature a macrocycle and/or a thiazepane ring.

Purpose of the Study:

  • To elucidate the mechanism of MUB and congener biosynthesis.
  • To understand the role of the MubD enzyme in lipopeptide formation.

Main Methods:

  • Biochemical analysis of the C-terminal reductase domain of MubD.
  • Investigation of spontaneous cyclization reactions in vitro.

Main Results:

  • The C-terminal reductase domain of MubD releases lipohexapeptide intermediates in an aldehyde form.
  • Aldehyde intermediates undergo spontaneous C-C macrocyclization.
  • Macrocyclized MUBs react with thiols to form diverse congeners via C-S bond formation and C-C bond cleavage.

Conclusions:

  • The biosynthesis of Mutanobactins involves a unique aldehyde-mediated macrocyclization pathway.
  • Enzymatic release of aldehyde intermediates by MubD is crucial for generating structural diversity in MUB congeners.

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