title: A recombinant Sp185/333 protein from the purple sea urchin has multitasking binding activities towards certain microbes and PAMPs.
abstract: The purple sea urchin, Strongylocentrotus purpuratus, possesses a sophisticated innate immune system that responds to microbes effectively by swift expression of the highly diverse Sp185/333 gene family. The Sp185/333 proteins are predicted to have anti-pathogen functions based on inducible gene expression and their significant sequence diversity. Sp185/333 proteins are all predicted to be intrinsically disordered and do not exhibit sequence similarities to other known proteins. To test the anti-pathogen hypothesis, a recombinant Sp185/333 protein, rSp0032, was evaluated and found to exhibit specific binding to marine Vibrio diazotrophicus and to Saccharomyces cerevisiae, but not to two Bacillus species. rSp0032 also binds to LPS, β-1,3-glucan and flagellin but not to peptidoglycan. rSp0032 binding to LPS can be competed by LPS, β-1,3-glucan and flagellin but not by peptidoglycan. We speculate that the predicted intrinsically disordered structure of rSp0032 may adapt to different conformations in binding to a limited number of PAMPs and pathogens. Given that rSp0032 binds to a range of targets, and that up to 260 different Sp185/333 proteins can be expressed per individual sea urchin, this family of immune response proteins may facilitate effective host protection against a broad array of potential pathogens encountered in the marine environment.
authors.affiliation: The George Washington University, Biological Sciences, Science Engineering Hall, 800 22nd St. NW, Washington DC 20052, United States.
authors.forename: Cheng Man
authors.initials: CM
authors.lastname: Lun
authors.affiliation: The George Washington University, Biological Sciences, Science Engineering Hall, 800 22nd St. NW, Washington DC 20052, United States.
authors.forename: Catherine S
authors.initials: CS
authors.lastname: Schrankel
authors.affiliation: The George Washington University, Biological Sciences, Science Engineering Hall, 800 22nd St. NW, Washington DC 20052, United States.
authors.forename: Hung-Yen
authors.initials: HY
authors.lastname: Chou
authors.affiliation: The George Washington University, Biological Sciences, Science Engineering Hall, 800 22nd St. NW, Washington DC 20052, United States.
authors.forename: Sandro
authors.initials: S
authors.lastname: Sacchi
authors.affiliation: The George Washington University, Biological Sciences, Science Engineering Hall, 800 22nd St. NW, Washington DC 20052, United States. Electronic address: csmith@gwu.edu.
authors.forename: L Courtney
authors.initials: LC
authors.lastname: Smith
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D012441:Saccharomyces cerevisiae / Q000276:immunology*; D047270:Strongylocentrotus purpuratus / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D014733:Vibrio / Q000276:immunology*
chemical_list: D023181:Antimicrobial Cationic Peptides; D011994:Recombinant Proteins
keywords: Bacterial binding; Immune response protein; Intrinsically disordered protein; PAMP binding