Engineering Styrene Monooxygenase for Biocatalysis: Reductase-Epoxidase Fusion Proteins

Publikation: Beitrag in FachzeitschriftForschungsartikelBeigetragenBegutachtung

Beitragende

  • Thomas Heine - , Technische Universität Bergakademie Freiberg (Autor:in)
  • Kathryn Tucker - , San Francisco State University (Autor:in)
  • Nonye Okonkwo - , San Francisco State University (Autor:in)
  • Berhanegebriel Assefa - , San Francisco State University (Autor:in)
  • Catleen Conrad - , Technische Universität Bergakademie Freiberg (Autor:in)
  • Anika Scholtissek - , Technische Universität Bergakademie Freiberg (Autor:in)
  • Michael Schlömann - , Technische Universität Bergakademie Freiberg (Autor:in)
  • George Gassner - , San Francisco State University (Autor:in)
  • Dirk Tischler - , Technische Universität Bergakademie Freiberg, San Francisco State University (Autor:in)

Abstract

The enantioselective epoxidation of styrene and related compounds by two-component styrene monooxygenases (SMOs) has targeted these enzymes for development as biocatalysts. In the present work, we prepare genetically engineered fusion proteins that join the C-terminus of the epoxidase (StyA) to the N-terminus of the reductase (StyB) through a linker peptide and demonstrate their utility as biocatalysts in the synthesis of Tyrain purple and other indigoid dyes. A single-vector expression system offers a simplified platform for transformation and expansion of the catalytic function of styrene monooxygenases, and the resulting fusion proteins are self-regulated and couple efficiently NADH oxidation to styrene epoxidation. We find that the reductase domain proceeds through a sequential ternary-complex mechanism at low FAD concentration and a double-displacement mechanism at higher concentrations of FAD. Single-turnover studies indicate an observed rate constant for FAD-to-FAD hydride transfer of ~8 s−1. This step is rate limiting in the styrene epoxidation reaction and helps to ensure that flavin reduction and styrene epoxidation reactions proceed without wasteful side reactions. Comparison of the reductase activity of the fusion proteins with the naturally occurring reductase, SMOB, and N-terminally histidine-tagged reductase, NSMOB, suggests that the observed changes in catalytic mechanism are due in part to an increase in flavin-binding affinity associated with the N-terminal extension of the reductase.

Details

OriginalspracheEnglisch
Seiten (von - bis)1590-1610
Seitenumfang21
FachzeitschriftApplied biochemistry and biotechnology : discoveries and technologies in the realm of application
Jahrgang181
Ausgabenummer4
PublikationsstatusVeröffentlicht - 1 Apr. 2017
Peer-Review-StatusJa
Extern publiziertJa

Externe IDs

PubMed 27830466
ORCID /0000-0002-7109-2788/work/142249499

Schlagworte

Schlagwörter

  • Epoxidation, Flavoprotein, Indigo, Monooxygenase, Protein engineering, Styrene

Bibliotheksschlagworte