A Hybrid Design for the Functional Assay of LvLRRm (Protein Containing LRR Domain) of the White Leg Shrimp, Litopenaeus vannamei

Abstract

In the crustacean immune system, leucine-rich repeat (LRR) is one of the major structures for recognizing pathogen-associated molecular patterns (PAMPs). LRR domain-containing proteins belong to the LRR family, which is a large group of proteins with more than 6000 genes in the database. They are involved in very diverse physiological functions, mainly by interacting with other proteins. In a previous study, the LvLRRm, a transmembrane protein containing only LRR domain, was identified in the white leg shrimp, Litopenaeus vannamei. Its versatile role in performing multiple immunomodulation activities has been reported. However, there is still a lack of research on its efficient function at the protein level. To investigate its interactions with other proteins, we applied a convenient method called the ‘Hybrid LRR technique’ to produce a recombinant LvLRRm. The LvLRRm and hagfish’s variable lymphocyte receptors (VLRs) fragments were fused to the conserved LxxLxLxxN motif while retaining the β-strand. In addition, we established interactions between hybrid proteins and the flagellin of Salmonella typhimurium by performing surface plasmon resonance (SPR) analysis. The results of the SPR analysis demonstrated notable affinity for both LvLRRm and hybrid proteins towards Salmonella flagellin. The designed LvLRRm hybrid proteins bring insight for universal applications without losing protein functions.