| Title: | "Crystal structure of the pheromone Er-13 from the ciliate Euplotes raikovi, with implications for a protein-protein association model in pheromone/receptor interactions" |
| Author(s): | Pedrini B; Finke AD; Marsh M; Luporini P; Vallesi A; Alimenti C; |
| Address: | "Paul Scherrer Institute, 5232 Villigen PSI, Switzerland. Paul Scherrer Institute, 5232 Villigen PSI, Switzerland; Macromolecular X-ray Science, Cornell High-energy Synchrotron Source, 161 Synchrotron Drive, Ithaca, NY 14853, USA. School of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino (MC), Italy. School of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino (MC), Italy. Electronic address: adriana.vallesi@unicam.it. School of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino (MC), Italy. Electronic address: claudio.alimenti@unicam.it" |
| DOI: | 10.1016/j.jsb.2021.107812 |
| ISSN/ISBN: | 1095-8657 (Electronic) 1047-8477 (Print) 1047-8477 (Linking) |
| Abstract: | "In the ciliate Euplotes raikovi, water-borne protein pheromones promote the vegetative cell growth and mating by competitively binding as autocrine and heterologous signals to putative cell receptors represented by membrane-bound pheromone isoforms. A previously determined crystal structure of pheromone Er-1 supported a pheromone/receptor binding model in which strong protein-protein interactions result from the cooperative utilization of two distinct types of contact interfaces that arrange molecules into linear chains, and these into two-dimensional layers. We have now determined the crystal structure of a new pheromone, Er-13, isolated from cultures that are strongly mating reactive withculturessource of pheromone Er-1.The comparison between the Er-1 and Er-13 crystal structuresreinforces the fundamental of the cooperative model of pheromone/receptor binding, in that the molecules arrange into linear chains taking a rigorously alternate opposite orientation reflecting the presumed mutual orientation of pheromone and receptor molecules on the cell surface. In addition, the comparison provides two new lines of evidence for a univocal rationalization of observations on the differentbehaviourbetween the autocrine and heterologous pheromone/receptor complexes. (i) In the Er-13 crystal, chains do not form layers which thus appear to be an over-structureunique tothe Er-1 crystal, not essential for the pheromone signalling mechanisms. (ii) In both crystal structures, the intra-chain interfaces are equally derived from burying amino-acid side-chains mostly residing on helix-3 of the three-helical pheromonefold. This helix is thus identified as the key structural motif underlying the pheromone activity, in line with its tight intra- and interspecificstructuralconservation" |
| Keywords: | *Euplotes/chemistry/metabolism Membrane Proteins/chemistry Pheromones/chemistry/metabolism Protein Binding Protozoan Proteins/metabolism Ciliate mating Protein-protein interactions Self/non-self recognition Signal proteins Three-helix proteins Water-borne; |
| Notes: | "MedlinePedrini, Bill Finke, Aaron D Marsh, May Luporini, Pierangelo Vallesi, Adriana Alimenti, Claudio eng P30 GM124166/GM/NIGMS NIH HHS/ Research Support, Non-U.S. Gov't 2021/11/21 J Struct Biol. 2022 Mar; 214(1):107812. doi: 10.1016/j.jsb.2021.107812. Epub 2021 Nov 17" |
