Crystal Structure of Escherichia coli SsuE: Defining a General Catalytic Cycle for FMN Reductases of the Flavodoxin-like Superfamily Public Deposited

http://ir.library.oregonstate.edu/concern/articles/sb397d495

This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by the American Chemical Society and can be found at:  http://pubs.acs.org/journal/bichaw.

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • The Escherichia coli sulfur starvation utilization (ssu) operon includes a two-component monooxygenase system made up of an NADPH-dependent FMN reductase, SsuE, and a monooxygenase, SsuD. SsuE is part of the flavodoxin-like superfamily, and we report here the crystal structures of its apo, FMN-bound and FMNH₂-bound forms at ~2 Å resolution. In the crystals, SsuE forms a tetramer that is a dimer of dimers similar to those of seen for homologous FMN-reductases, quinone reductases, and the WrbA family of enzymes. A π-helix present at the tetramer building interface is unique to the reductases from two component monooxygenase systems. Analytical ultracentrifugation studies of SsuE confirm a dimer-tetramer equilibrium exists in solution with FMN binding favoring the dimer. As the active site includes residues from both subunits, at least a dimeric association is required for the function of SsuE. The structures show that one FMN binds tightly in a deeply held site which makes available a second binding site, in which either a second FMN or the nicotinamide of NADPH can bind. The FMNH₂-bound structure shows subtle changes consistent with its weaker binding compared to FMN. Combining this information with published kinetics studies, we propose a general catalytic cycle for two-component reductases of the flavodoxin-like superfamily, by which the enzyme can potentially provide FMNH₂ to its partner monooxygenase by different routes depending on the FMN concentration and the presence of a partner monooxygenase.
Resource Type
DOI
Date Available
Date Issued
Citation
  • Driggers, C. M., Dayal, P. V., Ellis, H. R., & Karplus, P. A. (2014). Crystal structure of Escherichia coli SsuE: Defining a General Catalytic Cycle for FMN reductases of the Flavodoxin-like Superfamily. Biochemistry. 53(21), 3509-3519. doi:10.1021/bi500314f
Series
Rights Statement
Funding Statement (additional comments about funding)
Publisher
Peer Reviewed
Language
Digitization Specifications
  • π-helix π π-helix
Replaces

Relationships

In Administrative Set:
Last modified: 10/27/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items