Specific Molecular Signatures for Type II Crustins in Penaeid Shrimp Uncovered by the Identification of Crustin-Like Antimicrobial Peptides in Litopenaeus vannamei.

Cairé Barreto,Rafael Rosa,Jaqueline Coelho,Luciane Perazzolo,Jianbo Yuan,Jianhai Xiang

doi:10.3390/md16010031

Abstract

Crustins form a large family of antimicrobial peptides (AMPs) in crustaceans composed of four sub-groups (Types I-IV). Type II crustins (Type IIa or “Crustins” and Type IIb or “Crustin-like”) possess a typical hydrophobic N-terminal region and are by far the most representative sub-group found in penaeid shrimp. To gain insight into the molecular diversity of Type II crustins in penaeids, we identified and characterized a Type IIb crustin in Litopenaeus vannamei (Crustin-like Lv) and compared Type II crustins at both molecular and transcriptional levels. Although L. vannamei Type II crustins (Crustin Lv and Crustin-like Lv) are encoded by separate genes, they showed a similar tissue distribution (hemocytes and gills) and transcriptional response to the shrimp pathogens Vibrio harveyi and White spot syndrome virus (WSSV). As Crustin Lv, Crustin-like Lv transcripts were found to be present early in development, suggesting a maternal contribution to shrimp progeny. Altogether, our in silico and transcriptional data allowed to conclude that (1) each sub-type displays a specific amino acid signature at the C-terminal end holding both the cysteine-rich region and the whey acidic protein (WAP) domain, and that (2) shrimp Type II crustins evolved from a common ancestral gene that conserved a similar pattern of transcriptional regulation.

Highlights

Crustins are cysteine-rich antimicrobial peptides (AMPs) holding a typical whey acidic protein (WAP) domain [1]
We have evaluated the our study, the lack of induction of L. vannamei Type II crustins could be partly attributed to the time transcriptional response of L. vannamei Type II crustins at 48 h post-infections and it is probable that the course response of Type II crustins in the analyzed tissues and to the route of infection
We have identified for the first time a Type IIb crustin (Crustin-like Lv) in an Occidental penaeid, the Pacific white shrimp L. vannamei

Summary

Introduction

Crustins are cysteine-rich antimicrobial peptides (AMPs) holding a typical whey acidic protein (WAP) domain [1]. The WAP domain is a conserved motif containing eight cysteine residues, forming a characteristic four-disulfide core (4DSC) arrangement, that is found in many proteins exhibiting protease inhibitory properties or regulatory functions in growth and tissue differentiation [2]. These bioactive molecules were originally isolated from the hemolymph of the shore crab Carcinus maenas as a cationic 11.5-kDa peptide with specific activity against marine Gram-positive bacteria [3]. Crustins comprise a large and diverse family of gene-encoded AMPs in decapod crustaceans [8], but they are present.

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Conclusion