title: Evidence for structural constraint on ovulin, a rapidly evolving Drosophila melanogaster seminal protein.
abstract: The egg-laying hormone ovulin (Acp26Aa) is among the most rapidly evolving proteins in the Drosophila genome. Against the background of ovulin's high sequence variability within and between species, we have identified highly conserved motifs that may play an important structural role. Using yeast two-hybrid and GST-pull-down assays, we show that ovulin interacts with itself. The C terminus of ovulin is necessary and sufficient for self-interaction, with its C-terminal 45 aa playing a major role. Under nonreducing conditions, ovulin participates in a high-molecular-mass complex, suggesting that it occurs in an oligomeric form. One or more of three predicted coiled-coil domains in the C terminus of ovulin may be involved in its self-interaction. These structural elements are conserved between species despite an overall rapid pace of evolution in ovulin's primary sequence. We therefore suggest that domains involved in ovulin's self-interaction form a conserved structural backbone for the protein, resulting in greater evolutionary flexibility at other sites.
authors.affiliation: Department of Molecular Biology and Genetics, Biotechnology Building Room 423, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Wong
authors.forename: Shannon N
authors.initials: SN
authors.lastname: Albright
authors.forename: Mariana F
authors.initials: MF
authors.lastname: Wolfner
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D029721:Drosophila Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D007301:Insect Hormones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D029589:Seminal Plasma Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: C489171:Acp26Aa protein, Drosophila; D029721:Drosophila Proteins; D007301:Insect Hormones; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D029589:Seminal Plasma Proteins