title: Biochemical and structural study of the homologues of the thiol-disulfide oxidoreductase DsbA in Neisseria meningitidis.
abstract: Bacterial virulence depends on the correct folding of surface-exposed proteins, a process catalyzed by the thiol-disulfide oxidoreductase DsbA, which facilitates the synthesis of disulfide bonds in Gram-negative bacteria. The Neisseria meningitidis genome possesses three genes encoding active DsbAs: DsbA1, DsbA2 and DsbA3. DsbA1 and DsbA2 have been characterized as lipoproteins involved in natural competence and in host interactive biology, while the function of DsbA3 remains unknown. This work reports the biochemical characterization of the three neisserial enzymes and the crystal structures of DsbA1 and DsbA3. As predicted by sequence homology, both enzymes adopt the classic Escherichia coli DsbA fold. The most striking feature shared by all three proteins is their exceptional oxidizing power. With a redox potential of -80 mV, the neisserial DsbAs are the most oxidizing thioredoxin-like enzymes known to date. Consistent with these findings, thermal studies indicate that their reduced form is also extremely stable. For each of these enzymes, this study shows that a threonine residue found within the active-site region plays a key role in dictating this extraordinary oxidizing power. This result highlights how residues located outside the CXXC motif may influence the redox potential of members of the thioredoxin family.
authors.affiliation: Laboratoire des Protéines Membranaires, Institut de Biologie Structurale, CEA/CNRS/Université Joseph Fourier, 41 rue Jules Horowitz, 38027 Grenoble Cedex 01, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Lafaye
authors.forename: Thomas
authors.initials: T
authors.lastname: Iwema
authors.forename: Philippe
authors.initials: P
authors.lastname: Carpentier
authors.forename: Céline
authors.initials: C
authors.lastname: Jullian-Binard
authors.forename: J Simon
authors.initials: JS
authors.lastname: Kroll
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Collet
authors.forename: Laurence
authors.initials: L
authors.lastname: Serre
mesh_terms: D018360:Crystallography, X-Ray; D004795:Enzyme Stability; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009345:Neisseria meningitidis / Q000201:enzymology*; D010084:Oxidation-Reduction; D011490:Protein Disulfide Reductase (Glutathione) / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013816:Thermodynamics
chemical_list: D011490:Protein Disulfide Reductase (Glutathione)