| Title: | Aplysia temptin - the 'glue' in the water-borne attractin pheromone complex |
| Author(s): | Cummins SF; Xie F; de Vries MR; Annangudi SP; Misra M; Degnan BM; Sweedler JV; Nagle GT; Schein CH; |
| Address: | "Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555-0857, USA" |
| DOI: | 10.1111/j.1742-4658.2007.06070.x |
| ISSN/ISBN: | 1742-464X (Print) 1742-464X (Linking) |
| Abstract: | "Temptin, a component of the complex of water-borne protein pheromones that stimulate attraction and mating behavior in the marine mollusk Aplysia, has sequence homology to the epidermal growth factor (EGF)-like domains of higher organisms that mediate protein-cell surface contact during fertilization and blood coagulation. In this work, recombinant temptin for structural and functional studies was produced in Escherichia coli using a cold shock promoter and purified by RP-HPLC. CD spectra confirmed a predominantly beta-sheet structure. Two disulfide bonds were determined via limited proteolysis and MS. One internal disulfide (Cys57-Cys77) was predicted from initial alignments with class I EGF-like domains; the second, between Cys18 and Cys103, could protect temptin against proteolysis in seawater and stabilize its interacting surface. A three-dimensional model of temptin was prepared with our MPACK suite, based on the Ca(2+)-binding, EGF-like domain of the extracellular matrix protein fibrillin. Two temptin residues, Trp52 and Trp79, which align with cysteine residues conserved in fibrillins, lie adjacent to and could stabilize the disulfide bonds and a proposed metal-binding loop. The water-borne pheromone attractin in egg cordon eluates is complexed with other proteins. Docking results with our model and the NMR structure of attractin suggest that one face of temptin interacts with the pheromone, perhaps controlling its access to the cellular receptors. Gel shifts confirmed that temptin complexes with wild-type attractin. These results indicate that temptin, analogous to the role of fibrillin in controlling transforming growth factor-beta concentration, modulates pheromone signaling by direct binding to attractin" |
| Keywords: | "Amino Acid Sequence Animals Aplysia/drug effects/*physiology Blotting, Northern Circular Dichroism Disulfides/metabolism Glycoproteins/*physiology Models, Molecular Molecular Sequence Data Pheromones/*pharmacology Protein Conformation Sequence Homology, A;" |
| Notes: | "MedlineCummins, Scott F Xie, Fang de Vries, Melissa R Annangudi, Suresh P Misra, Milind Degnan, Bernard M Sweedler, Jonathan V Nagle, Gregg T Schein, Catherine H eng R01 NS031609/NS/NINDS NIH HHS/ R33 DK070285/DK/NIDDK NIH HHS/ DK070285/DK/NIDDK NIH HHS/ R01AI064913-01/AI/NIAID NIH HHS/ Research Support, N.I.H., Extramural Research Support, U.S. Gov't, Non-P.H.S. England 2007/09/27 FEBS J. 2007 Oct; 274(20):5425-37. doi: 10.1111/j.1742-4658.2007.06070.x. Epub 2007 Sep 26" |
