The first mollusk spätzle homolog gene in the clam, Paphia undulate. Issue 2 (December 2015)

• Record Type: Journal Article
• Authors: Yu, Mingjia; Zhang, Yuehuan; Tang, Xu; Ren, Jun; Zhang, Yang
• Is Part Of: Fish & shellfish immunology. Volume 47:Issue 2(2015:Dec.)
• Page Start: 712
• Page End: 716
• Publication Date: 2015-12
• Subjects: Spätzle -- Paphia undulate -- Toll-like receptor -- Ligand -- Innate immune; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2015.10.017
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: Spätzle, is the only identified endogenous Toll receptor ligand, plays a critical role in initiatinge innate immune responses and controlling dorsal-ventral axis formation in Drosophila . Here we identified the first spätzle gene homolog, Pu-Spz, in the marine mollusk Paphia undulate . The full-length of Pu-Spz cDNA is 1248 bp, including an open reading frame (ORF) of 702 bp, a 5′-untranslated region (UTR) of 26 bp and a 3′-UTR of 203 bp. The ORF encodes a 233-amino-acid protein with conserved domains; it includes a putative signal peptide and a C-terminal cystine-knot. Sequence alignment revealed that the cystine-knot domain of Pu-Spz contains six highly conserved Cys residues, which maintain a molecular conformation suitable for Toll receptor binding. Unlike Spätzle, Pu-Spz lacks a seventh Cys residue, which is essential for forming intermolecular disulfide bridge. Phylogenetic analysis revealed that Pu-Spz is closer to the homologs found in crustaceans than to those in the insect branch. Transcript abundance of Pu-Spz was increased after challenging P. undulate with either heat-killed Listeria monocytogenes or heat-killed Vibrio alginolyticus, suggesting Spätzle is involved in P. undulate host defense. Our results demonstrate convergent evolution of the spätzle-Toll system between the mollusk and arthropod lineages. Highlights: First spätzle homolog was identified in one marine mollusk, Paphia undulate . Spätzle were involved in the host defense against both G+ and G− bacteria. Spätzle-Toll system may convergent evolve in the lineage of mollusk and arthropod.