title: A Study of the Dynamics of the Heme Pocket and C-helix in CooA upon CO Dissociation Using Time-Resolved Visible and UV Resonance Raman Spectroscopy.
abstract: CooA is a CO-sensing transcriptional activator from the photosynthetic bacterium Rhodospirillum rubrum that binds CO at the heme iron. The heme iron in ferrous CooA has two axial ligands: His77 and Pro2. CO displaces Pro2 and induces a conformational change in CooA. The dissociation of CO and/or ligation of the Pro2 residue are believed to trigger structural changes in the protein. Visible time-resolved resonance Raman spectra obtained in this study indicated that the ν(Fe-His) mode, arising from the proximal His77-iron stretch, does not shift until 50 μs after the photodissociation of CO. Ligation of the Pro2 residue to the heme iron was observed around 50 μs after the photodissociation of CO, suggesting that the ν(Fe-His) band exhibits no shift until the ligation of Pro2. UV resonance Raman spectra suggested structural changes in the vicinity of Trp110 in the C-helix upon CO binding, but no or very small spectral changes in the time-resolved UV resonance Raman spectra were observed from 100 ns to 100 μs after the photodissociation of CO. These results strongly suggest that the conformational change of CooA is induced by the ligation of Pro2 to the heme iron.
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University , 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Otomo
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University , 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Haruto
authors.initials: H
authors.lastname: Ishikawa
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University , 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Misao
authors.initials: M
authors.lastname: Mizuno
authors.affiliation: RIKEN SPring-8 Center , 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors.forename: Tetsunari
authors.initials: T
authors.lastname: Kimura
authors.affiliation: RIKEN SPring-8 Center , 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Kubo
authors.affiliation: RIKEN SPring-8 Center , 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Shiro
authors.affiliation: Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences , 5-1 Higashiyama, Myodaiji, Okazaki 444-8786, Japan.
authors.forename: Shigetoshi
authors.initials: S
authors.lastname: Aono
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University , 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Mizutani
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects*; D002245:Carbon Dioxide / Q000737:chemistry*; D004926:Escherichia coli; D006418:Heme / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects; D006420:Hemeproteins / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects*; D006860:Hydrogen Bonding; D055668:Photochemical Processes; D011487:Protein Conformation; D012247:Rhodospirillum rubrum; D013059:Spectrum Analysis, Raman / Q000379:methods; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects*
chemical_list: D001426:Bacterial Proteins; C108776:CooA protein, Rhodospirillum rubrum; D006420:Hemeproteins; D015534:Trans-Activators; D002245:Carbon Dioxide; D006418:Heme