title: Structure of the redox sensor domain of Methylococcus capsulatus (Bath) MmoS.
abstract: MmoS from Methylococcus capsulatus (Bath) is the multidomain sensor protein of a two-component signaling system proposed to play a role in the copper-mediated regulation of soluble methane monooxygenase (sMMO). MmoS binds an FAD cofactor within its N-terminal tandem Per-Arnt-Sim (PAS) domains, suggesting that it functions as a redox sensor. The crystal structure of the MmoS tandem PAS domains, designated PAS-A and PAS-B, has been determined to 2.34 A resolution. Both domains adopt the typical PAS domain alpha/beta topology and are structurally similar. The two domains are linked by a long alpha helix and do not interact with one another. The FAD cofactor is housed solely within PAS-A and is stabilized by an extended hydrogen bonding network. The overall fold of PAS-A is similar to those of other flavin-containing PAS domains, but homodimeric interactions in other structures are not observed in the MmoS sensor, which crystallized as a monomer. The structure both provides new insight into the architecture of tandem PAS domains and suggests specific residues that may play a role in MmoS FAD redox chemistry and subsequent signal transduction.
authors.affiliation: Department of Biochemistry, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Uchechi E
authors.initials: UE
authors.lastname: Ukaegbu
authors.forename: Amy C
authors.initials: AC
authors.lastname: Rosenzweig
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D020619:Methylococcus capsulatus / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000737:chemistry* / Q000235:genetics; D054730:Protein Interaction Domains and Motifs; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D040681:Structural Homology, Protein
chemical_list: D011994:Recombinant Proteins; D005182:Flavin-Adenine Dinucleotide; D010105:Oxygenases; C021555:methane monooxygenase