title: Radiation Damage and Racemic Protein Crystallography Reveal the Unique Structure of the GASA/Snakin Protein Superfamily.
abstract: Proteins from the GASA/snakin superfamily are common in plant proteomes and have diverse functions, including hormonal crosstalk, development, and defense. One 63-residue member of this family, snakin-1, an antimicrobial protein from potatoes, has previously been chemically synthesized in a fully active form. Herein the 1.5 Å structure of snakin-1, determined by a novel combination of racemic protein crystallization and radiation-damage-induced phasing (RIP), is reported. Racemic crystals of snakin-1 and quasi-racemic crystals incorporating an unnatural 4-iodophenylalanine residue were prepared from chemically synthesized d- and l-proteins. Breakage of the C-I bonds in the quasi-racemic crystals facilitated structure determination by RIP. The crystal structure reveals a unique protein fold with six disulfide crosslinks, presenting a distinct electrostatic surface that may target the protein to microbial cell surfaces.
authors.affiliation: School of Biological Sciences, The University of Auckland, 3A Symonds St, Auckland Central, 1010, New Zealand.
authors.forename: Ho
authors.initials: H
authors.lastname: Yeung
authors.affiliation: School of Biological Sciences, The University of Auckland, 3A Symonds St, Auckland Central, 1010, New Zealand. c.squire@auckland.ac.nz.|Maurice Wilkins Centre for Molecular Biodiscovery, Thomas Building Level 2, 3A Symonds St, Auckland Central, 1010, New Zealand. c.squire@auckland.ac.nz.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Squire
authors.affiliation: School of Biological Sciences, The University of Auckland, 3A Symonds St, Auckland Central, 1010, New Zealand.
authors.forename: Yuliana
authors.initials: Y
authors.lastname: Yosaatmadja
authors.affiliation: Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria, 3168, Australia.
authors.forename: Santosh
authors.initials: S
authors.lastname: Panjikar
authors.affiliation: Centro de Biotecnología y Genómica de Plantas (UPM-INIA), Universidad Politécnica de Madrid (UPM), Campus Montegancedo, M-40 (Km 38), 28223-Pozuelo de Alarcón, Madrid, Spain.
authors.forename: Gemma
authors.initials: G
authors.lastname: López
authors.affiliation: Centro de Biotecnología y Genómica de Plantas (UPM-INIA), Universidad Politécnica de Madrid (UPM), Campus Montegancedo, M-40 (Km 38), 28223-Pozuelo de Alarcón, Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Molina
authors.affiliation: School of Biological Sciences, The University of Auckland, 3A Symonds St, Auckland Central, 1010, New Zealand.|Maurice Wilkins Centre for Molecular Biodiscovery, Thomas Building Level 2, 3A Symonds St, Auckland Central, 1010, New Zealand.
authors.forename: Edward N
authors.initials: EN
authors.lastname: Baker
authors.affiliation: School of Chemical Sciences, The University of Auckland, 23 Symonds St, Auckland Central, 1010, New Zealand.|Maurice Wilkins Centre for Molecular Biodiscovery, Thomas Building Level 2, 3A Symonds St, Auckland Central, 1010, New Zealand.
authors.forename: Paul W R
authors.initials: PW
authors.lastname: Harris
authors.affiliation: School of Chemical Sciences, The University of Auckland, 23 Symonds St, Auckland Central, 1010, New Zealand. m.brimble@auckland.ac.nz.|Maurice Wilkins Centre for Molecular Biodiscovery, Thomas Building Level 2, 3A Symonds St, Auckland Central, 1010, New Zealand. m.brimble@auckland.ac.nz.
authors.forename: Margaret A
authors.identifier: 0000-0002-7086-4096
authors.initials: MA
authors.lastname: Brimble
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods; D008958:Models, Molecular; D010940:Plant Proteins / Q000737:chemistry*; D011487:Protein Conformation; D011198:Solanum tuberosum / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D010940:Plant Proteins; C117071:SN1 protein, Solanum tuberosum
keywords: peptides; protein structures; racemic protein crystallography; solid-phase synthesis