title: Dynamic nature of disulphide bond formation catalysts revealed by crystal structures of DsbB.
abstract: In the Escherichia coli system catalysing oxidative protein folding, disulphide bonds are generated by the cooperation of DsbB and ubiquinone and transferred to substrate proteins through DsbA. The structures solved so far for different forms of DsbB lack the Cys104-Cys130 initial-state disulphide that is directly donated to DsbA. Here, we report the 3.4 A crystal structure of a DsbB-Fab complex, in which DsbB has this principal disulphide. Its comparison with the updated structure of the DsbB-DsbA complex as well as with the recently reported NMR structure of a DsbB variant having the rearranged Cys41-Cys130 disulphide illuminated conformational transitions of DsbB induced by the binding and release of DsbA. Mutational studies revealed that the membrane-parallel short alpha-helix of DsbB has a key function in physiological electron flow, presumably by controlling the positioning of the Cys130-containing loop. These findings demonstrate that DsbB has developed the elaborate conformational dynamism to oxidize DsbA for continuous protein disulphide bond formation in the cell.
authors.affiliation: Division of Protein Chemistry, Post-Genome Science Center, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan. inaba-k@bioreg.kyushu-u.ac.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Inaba
authors.forename: Satoshi
authors.initials: S
authors.lastname: Murakami
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nakagawa
authors.forename: Hiroka
authors.initials: H
authors.lastname: Iida
authors.forename: Mai
authors.initials: M
authors.lastname: Kinjo
authors.forename: Koreaki
authors.initials: K
authors.lastname: Ito
authors.forename: Mamoru
authors.initials: M
authors.lastname: Suzuki
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D055162:Biocatalysis; D002462:Cell Membrane / Q000201:enzymology; D003460:Crystallization; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D019704:Protein Disulfide-Isomerases / Q000737:chemistry / Q000378:metabolism; D017433:Protein Structure, Secondary; D021381:Protein Transport; D013329:Structure-Activity Relationship; D014451:Ubiquinone / Q000737:chemistry / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004220:Disulfides; C079503:DsbB protein, Bacteria; D029968:Escherichia coli Proteins; D007140:Immunoglobulin Fab Fragments; D008565:Membrane Proteins; D014451:Ubiquinone; D019704:Protein Disulfide-Isomerases; C526648:dsbA protein, E coli; D003545:Cysteine