title: NMR solution structure of attractin, a water-borne protein pheromone from the mollusk Aplysia californica.
abstract: Water-borne protein pheromones are essential for coordination of reproductive activities in many marine organisms. In this paper, we describe the first structure of a pheromone protein from a marine organism, that of attractin (58 residues) from Aplysia californica. The NMR solution structure was determined from TOCSY, NOESY, and DQF-COSY measurements of recombinant attractin expressed in insect cells. The sequential resonance assignments were done with standard manual procedures. Approximately 90% of the 949 unambiguous NOESY cross-peaks were assigned automatically with simultaneous three-dimensional structure calculation using our NOAH/DIAMOD/FANTOM program suite. The final bundle of energy-refined structures is well-defined, with an average rmsd value to the mean structure of 0.72 +/- 0.12 A for backbone and 1.32 +/- 0.11 A for heavy atoms for amino acids 3-47. Attractin contains two antiparallel helices, made up of residues Ile9-Gln16 and I30-S36. The NMR distance constraints are consistent with the three disulfide bonds determined by mass spectroscopy (C4-C41, C13-C33, and C20-C26), where the first two could be directly determined from NOESY cross-peaks between CH beta protons of the corresponding cysteines. The second helix contains the (L/I)(29)IEECKTS(36) sequence conserved in attractins from five species of Aplysia that could interact with the receptor. The sequence and structure of this region are similar to those of the recognition helix of the Er-11 pheromone of the unicellular ciliate Euplotes raikovi, suggesting a possible common pathway for intercellular communication of these two distinct pheromone families.
authors.affiliation: Sealy Center for Structural Biology, Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston, Texas 77555, USA.
authors.forename: Ravindranath
authors.initials: R
authors.lastname: Garimella
authors.forename: Yuan
authors.initials: Y
authors.lastname: Xu
authors.forename: Catherine H
authors.initials: CH
authors.lastname: Schein
authors.forename: Krishna
authors.initials: K
authors.lastname: Rajarathnam
authors.forename: Gregg T
authors.initials: GT
authors.lastname: Nagle
authors.forename: Sherry D
authors.initials: SD
authors.lastname: Painter
authors.forename: Werner
authors.initials: W
authors.lastname: Braun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001048:Aplysia / Q000737:chemistry*; D006023:Glycoproteins / Q000737:chemistry* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010675:Pheromones / Q000737:chemistry* / Q000378:metabolism; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D006023:Glycoproteins; D010675:Pheromones; D011994:Recombinant Proteins; C112624:attractin protein, Aplysia; D014867:Water