title: Structure of green-type Rubisco activase from tobacco.
abstract: Rubisco, the enzyme that catalyzes the fixation of atmospheric CO(2) in photosynthesis, is subject to inactivation by inhibitory sugar phosphates. Here we report the 2.95-Å crystal structure of Nicotiana tabacum Rubisco activase (Rca), the enzyme that facilitates the removal of these inhibitors. Rca from tobacco has a classical AAA(+)-protein domain architecture. Although Rca populates a range of oligomeric states when in solution, it forms a helical arrangement with six subunits per turn when in the crystal. However, negative-stain electron microscopy of the active mutant R294V suggests that Rca functions as a hexamer. The residues determining species specificity for Rubisco are located in a helical insertion of the C-terminal domain and probably function in conjunction with the N-domain in Rubisco recognition. Loop segments exposed toward the central pore of the hexamer are required for the ATP-dependent remodeling of Rubisco, resulting in the release of inhibitory sugar.
authors: Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany.
authors: Mathias
authors: M
authors: Stotz
authors: Oliver
authors: O
authors: Mueller-Cajar
authors: Susanne
authors: S
authors: Ciniawsky
authors: Petra
authors: P
authors: Wendler
authors: F Ulrich
authors: FU
authors: Hartl
authors: Andreas
authors: A
authors: Bracher
authors: Manajit
authors: M
authors: Hayer-Hartl
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010788:Photosynthesis / Q000502:physiology; D010940:Plant Proteins / Q000737:chemistry* / Q000502:physiology; D017434:Protein Structure, Tertiary; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism*; D016415:Sequence Alignment; D010959:Tissue Plasminogen Activator / Q000737:chemistry* / Q000502:physiology; D014026:Nicotiana / Q000201:enzymology* / Q000378:metabolism
chemical_list: D010940:Plant Proteins; C054765:rca protein, plant; D010959:Tissue Plasminogen Activator; D012273:Ribulose-Bisphosphate Carboxylase