title: Solution NMR and molecular dynamics reveal a persistent alpha helix within the dynamic region of PsbQ from photosystem II of higher plants.
abstract: The extrinsic proteins of photosystem II of higher plants and green algae PsbO, PsbP, PsbQ, and PsbR are essential for stable oxygen production in the oxygen evolving center. In the available X-ray crystallographic structure of higher plant PsbQ residues S14-Y33 are missing. Building on the backbone NMR assignment of PsbQ, which includes this "missing link", we report the extended resonance assignment including side chain atoms. Based on nuclear Overhauser effect spectra a high resolution solution structure of PsbQ with a backbone RMSD of 0.81 Å was obtained from torsion angle dynamics. Within the N-terminal residues 1-45 the solution structure deviates significantly from the X-ray crystallographic one, while the four-helix bundle core found previously is confirmed. A short α-helix is observed in the solution structure at the location where a β-strand had been proposed in the earlier crystallographic study. NMR relaxation data and unrestrained molecular dynamics simulations corroborate that the N-terminal region behaves as a flexible tail with a persistent short local helical secondary structure, while no indications of forming a β-strand are found.
authors.affiliation: Institute of Organic Chemistry, Johannes Kepler University Linz, Linz, 4040, Austria.|Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Rathner
authors.affiliation: Institute of Organic Chemistry, Johannes Kepler University Linz, Linz, 4040, Austria.
authors.forename: Adriana
authors.initials: A
authors.lastname: Rathner
authors.affiliation: Institute of Organic Chemistry, Johannes Kepler University Linz, Linz, 4040, Austria.|Lohmann Animal Health, Cuxhaven, 27472, Germany.
authors.forename: Michaela
authors.initials: M
authors.lastname: Horničáková
authors.affiliation: Scientific Computing, Johannes Kepler University Linz, Linz, 4040, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Wohlschlager
authors.affiliation: Institute of Organic Chemistry, Johannes Kepler University Linz, Linz, 4040, Austria.
authors.forename: Kousik
authors.initials: K
authors.lastname: Chandra
authors.affiliation: Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.|Center of Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Nové Hrady, Czech Republic.
authors.forename: Jaroslava
authors.initials: J
authors.lastname: Kohoutová
authors.affiliation: Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.|Center of Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Nové Hrady, Czech Republic.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Ettrich
authors.affiliation: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Aalborg, 9220, Denmark.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Wimmer
authors.affiliation: Institute of Organic Chemistry, Johannes Kepler University Linz, Linz, 4040, Austria.|Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
authors.forename: Norbert
authors.initials: N
authors.lastname: Müller
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D056004:Molecular Dynamics Simulation; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012996:Solutions; D018724:Spinacia oleracea / Q000235:genetics / Q000378:metabolism; D013816:Thermodynamics
chemical_list: D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D011994:Recombinant Proteins; D012996:Solutions
keywords: Spinacia oleracea; dynamic N-terminus; extrinsic photosynthetic protein; hydrogen bond dynamics; intrinsic disorder; solution structure