Structure of alpha-glycerophosphate Oxidase from Streptococcus sp.: a Template for the Mitochondrial alpha-glycerophosphate Dehydrogenase

Journal Article · Sat Dec 31 04:00:00 EST 2011 · Biochemistry (Eaton)

OSTI ID:1041941

Colussi, T; Parsonage, D; Boles, W; Matsuoka, T; Mallett, T; Karplus, P; Claiborne, A

The FAD-dependent {alpha}-glycerophosphate oxidase (GlpO) from Enterococcus casseliflavus and Streptococcus sp. was originally studied as a soluble flavoprotein oxidase; surprisingly, the GlpO sequence is 30-43% identical to those of the {alpha}-glycerophosphate dehydrogenases (GlpDs) from mitochondrial and bacterial sources. The structure of a deletion mutant of Streptococcus sp. GlpO (GlpO{Delta}, lacking a 50-residue insert that includes a flexible surface region) has been determined using multiwavelength anomalous dispersion data and refined at 2.3 {angstrom} resolution. Using the GlpO{Delta} structure as a search model, we have also determined the intact GlpO structure, as refined at 2.4 {angstrom} resolution. The first two domains of the GlpO fold are most closely related to those of the flavoprotein glycine oxidase, where they function in FAD binding and substrate binding, respectively; the GlpO C-terminal domain consists of two helix bundles and is not closely related to any known structure. The flexible surface region in intact GlpO corresponds to a segment of missing electron density that links the substrate-binding domain to a {beta}{beta}{alpha} element of the FAD-binding domain. In accordance with earlier biochemical studies (stabilizations of the covalent FAD-N5-sulfite adduct and p-quinonoid form of 8-mercapto-FAD), Ile430-N, Thr431-N, and Thr431-OG are hydrogen bonded to FAD-O2{alpha} in GlpO{Delta}, stabilizing the negative charge in these two modified flavins and facilitating transfer of a hydride to FAD-N5 (from Glp) as well. Active-site overlays with the glycine oxidase-N-acetylglycine and d-amino acid oxidase-d-alanine complexes demonstrate that Arg346 of GlpO{Delta} is structurally equivalent to Arg302 and Arg285, respectively; in both cases, these residues interact directly with the amino acid substrate or inhibitor carboxylate. The structural and functional divergence between GlpO and the bacterial and mitochondrial GlpDs is also discussed.

• Research Organization: BROOKHAVEN NATIONAL LABORATORY (BNL)
• Sponsoring Organization: USDOE SC OFFICE OF SCIENCE (SC)
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 1041941
• Report Number(s): BNL--97619-2012-JA
• Journal Information: Biochemistry (Eaton), Journal Name: Biochemistry (Eaton) Journal Issue: 3 Vol. 47; ISSN 0006-2960; ISSN BICHAW
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
ADDUCTS
AMINO ACIDS
ELECTRON DENSITY
FUNCTIONALS
GLYCINE
HYDRIDES
HYDROGEN
ISOALLOXAZINES
MUTANTS
OXIDASES
OXIDOREDUCTASES
RESIDUES
RESOLUTION
STREPTOCOCCUS
SUBSTRATES