6DQI

Crystal structure of SsuE FMN reductase Y118A mutant in apo form.

Summary for 6DQI

• Entry DOI: 10.2210/pdb6dqi/pdb
• Descriptor: FMN reductase (NADPH), SULFATE ION (3 entities in total)
• Functional Keywords: reductase, fmn, nad(p)h, flavoprotein, oxidoreductase
• Biological source: Escherichia coli (strain K12)
• Total number of polymer chains: 2
• Total formula weight: 42468.41

Authors

McFarlane, J.S.,Ellis, H.R.,Lamb, A.L. (deposition date: 2018-06-11, release date: 2019-01-09, Last modification date: 2023-10-11)

Primary citation

McFarlane, J.S.,Hagen, R.A.,Chilton, A.S.,Forbes, D.L.,Lamb, A.L.,Ellis, H.R.
Not as easy as pi : An insertional residue does not explain the pi-helix gain-of-function in two-component FMN reductases.
Protein Sci., 28:123-134, 2019

PubMed Abstract: The π-helix located at the tetramer interface of two-component FMN-dependent reductases contributes to the structural divergence from canonical FMN-bound reductases within the NADPH:FMN reductase family. The π-helix in the SsuE FMN-dependent reductase of the alkanesulfonate monooxygenase system has been proposed to be generated by the insertion of a Tyr residue in the conserved α4-helix. Variants of Tyr118 were generated, and their X-ray crystal structures determined, to evaluate how these alterations affect the structural integrity of the π-helix. The structure of the Y118A SsuE π-helix was converted to an α-helix, similar to the FMN-bound members of the NADPH:FMN reductase family. Although the π-helix was altered, the FMN binding region remained unchanged. Conversely, deletion of Tyr118 disrupted the secondary structural properties of the π-helix, generating a random coil region in the middle of helix 4. Both the Y118A and Δ118 SsuE SsuE variants crystallize as a dimer. The MsuE FMN reductase involved in the desulfonation of methanesulfonates is structurally similar to SsuE, but the π-helix contains a His insertional residue. Exchanging the π-helix insertional residue of each enzyme did not result in equivalent kinetic properties. Structure-based sequence analysis further demonstrated the presence of a similar Tyr residue in an FMN-bound reductase in the NADPH:FMN reductase family that is not sufficient to generate a π-helix. Results from the structural and functional studies of the FMN-dependent reductases suggest that the insertional residue alone is not solely responsible for generating the π-helix, and additional structural adaptions occur to provide the altered gain of function.

PubMed: 30171650
DOI: 10.1002/pro.3504

Experimental method

X-RAY DIFFRACTION (1.95 Å)