Molecular characterization of an LRR-only protein gene in Pacific white shrimp Litopenaeus vannamei: Sequence feature, expression pattern, and protein activity.

Leucine-rich repeat (LRR)-only proteins have been proved to be involved in the innate immune responses as they could mediate protein-protein or protein-ligand interactions. In the present study, a novel LRR-only protein (Lv LRRop-1) was identified and characterized from Pacific white shrimp Litopenaeus vannamei. The complete cDNA sequence of Lv LRRop-1 contains an open reading frame (ORF) of 1488 bp, which encoded a polypeptide of 495 amino acids with a predicted molecular mass of 55.67 kDa and a calculated theoretical isoelectric point of 6.435. There are five LRR motifs, six LRR_TYP motifs in the protein sequence of Lv LRRop-1 with consensus signature sequences of LxxLxxLxLxxNxL. The Lv LRRop-1 mRNA transcripts could be detected in all the tested tissues, including eyestalk, gill, gonad, heart, hemocytes, hepatopancreas, intestine, muscle, nerve and stomach, especially highest in hemocytes and hepatopancreas. The mRNA transcripts of Lv LRRop-1 increased within the first 6 h in hemocytes and hepatopancreas after Vibrio parahaemolyticus or white spot syndrome virus (WSSV) challenges. The recombinant Lv LRRop-1 could bind four typical pathogen-associated molecular patterns (PAMPs), including lipopolysaccharide (LPS), peptidoglycan (PGN), glucan (GLU) and polycytidine-polycytidylic acid (poly IC), in a dose-dependent manner, and inhibit the growth of bacteria Micrococcus luteu s. These data indicated that Lv LRRop-1 could play a pivotal role in the innate immune response of shrimps as a kind of pattern recognition receptor (PRR). • Molecular characterization of a novel LRR-only protein in Litopenaeus vannamei • Its expression profiles and pattern recognition ligands spectrum were investigated • It could inhibit the growth of bacteria Micrococcus luteu s [ABSTRACT FROM AUTHOR]