title: Structure of the insect cytokine peptide plasmatocyte-spreading peptide 1 from Pseudoplusia includens.
abstract: The structure of the recently identified plasmatocyte spreading peptide from the moth Pseudoplusia includens (PSP1) has been determined by NMR spectroscopy. This novel insect cytokine consists of 23 amino acid residues and a single disulfide bond. Torsion angle dynamics calculations utilizing a total of 337 distance constraints yielded an ensemble of 30 structures with an average backbone root mean square deviation for residues 7-22 of 0.18 A from the mean structure. The structure consists of a disordered N-terminal region and a well defined core that is stabilized by numerous hydrophobic interactions and a short beta-hairpin. Structural comparisons confirm that PSP1 adopts an epidermal growth factor (EGF)-like fold with close similarity to the C-terminal subdomain of EGF-like module 5 of human thrombomodulin. The combination of the three-dimensional structure of PSP1 and the extensive literature on EGF-receptor interactions should accelerate the process of identifying the specific residues responsible for receptor binding activity of this family of immunoregulatory peptides.
authors.affiliation: National Magnetic Resonance Facility at Madison, Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706-1544, USA. volkman@nmrfam.wisc.edu
authors.forename: B F
authors.initials: BF
authors.lastname: Volkman
authors.forename: M E
authors.initials: ME
authors.lastname: Anderson
authors.forename: K D
authors.initials: KD
authors.lastname: Clark
authors.forename: Y
authors.initials: Y
authors.lastname: Hayakawa
authors.forename: M R
authors.initials: MR
authors.lastname: Strand
authors.forename: J L
authors.initials: JL
authors.lastname: Markley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004815:Epidermal Growth Factor / Q000737:chemistry; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009036:Moths / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid