title: The Lepidopteran endoribonuclease-U domain protein P102 displays dramatically reduced enzymatic activity and forms functional amyloids.
abstract: Hemocytes of Heliothis virescens (F.) (Lepidoptera, Noctuidae) larvae produce a protein, P102, with a putative endoribonuclease-U domain. In previous works we have shown that P102 is involved in Lepidopteran immune response by forming amyloid fibrils, which catalyze and localize melanin deposition around non-self intruders during encapsulation, preventing harmful systemic spreading. Here we demonstrate that P102 belongs to a new class of proteins that, at least in Lepidoptera, has a diminished endoribonuclease-U activity probably due to the lack of two out of five catalytically essential residues. We show that the P102 homolog from Trichoplusia ni (Lepidoptera, Noctuidae) displays catalytic site residues identical to P102, a residual endoribonuclease-U activity and the ability to form functional amyloids. On the basis of these results as well as sequence and structural analyses, we hypothesize that all the Lepidoptera endoribonuclease-U orthologs with catalytic site residues identical to P102 form a subfamily with similar function.
authors.affiliation: Università della Basilicata, Dipartimento di Scienze, via dell'Ateneo Lucano 10, 85100 Potenza, Italy.
authors.forename: Mariarosa
authors.initials: M
authors.lastname: Pascale
authors.affiliation: Università della Basilicata, Dipartimento di Scienze, via dell'Ateneo Lucano 10, 85100 Potenza, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Laurino
authors.affiliation: Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Strasse 8, 07745 Jena, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Vogel
authors.affiliation: Università dell'Insubria, Dipartimento di Biotecnologie e Scienze della Vita, via Dunant 3, 21100 Varese, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Grimaldi
authors.affiliation: Università della Basilicata, Dipartimento di Scienze, via dell'Ateneo Lucano 10, 85100 Potenza, Italy.
authors.forename: Magnus
authors.initials: M
authors.lastname: Monné
authors.affiliation: Università della Basilicata, Dipartimento di Scienze, via dell'Ateneo Lucano 10, 85100 Potenza, Italy.
authors.forename: Lea
authors.initials: L
authors.lastname: Riviello
authors.affiliation: Università dell'Insubria, Dipartimento di Biotecnologie e Scienze della Vita, via Dunant 3, 21100 Varese, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Tettamanti
authors.affiliation: Università della Basilicata, Dipartimento di Scienze, via dell'Ateneo Lucano 10, 85100 Potenza, Italy. Electronic address: patrizia.falabella@unibas.it.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Falabella
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D004722:Endoribonucleases / Q000378:metabolism; D006434:Hemocytes / Q000378:metabolism; D019476:Insect Proteins / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009036:Moths / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D010802:Phylogeny; D017434:Protein Structure, Tertiary
chemical_list: D000682:Amyloid; D019476:Insect Proteins; D004722:Endoribonucleases; C029494:ribonuclease U
keywords: Amyloids; Endoribonuclease-U; Heliothis virescens; Immunity; Lepidoptera; Trichoplusia ni