Molecular and Functional Diversity of Crustin-Like Genes in the Shrimp Litopenaeus vannamei.

Fuhua Li,Yang Yu,Xinjia Lv,Shihao Li,Xiaojun Zhang

doi:10.3390/md18070361

Abstract

Crustins are crustacean cationic cysteine-rich antimicrobial peptides that contain one or two whey acidic protein (WAP) domain(s) at the carboxyl terminus and mainly show antimicrobial and/or proteinase inhibitory activities. Here, we performed genome and transcriptome screening and identified 34 full-length crustin-like encoding genes in Litopenaeus vannamei. Multiple sequence analysis of the deduced mature peptides revealed that these putative crustins included 10 type Ia, two type Ib, one type Ic, 11 type IIa, three type IIb, four type III, one type IV, one type VI, and one type VII. These putative crustins were clustered into different groups. Phylogenetic analysis, considering their domain composition, showed that different types of crustin-like genes in crustaceans might be originated from the WAP core region, along with sequence insertion, duplication, deletion, and amino acid substitution. Tissue distribution analysis suggested that most crustin-like genes were mainly detected in immune-related tissues while several crustin-like genes exhibited tissue-specific expression patterns. Quantitative PCR analysis on 15 selected crustin-like genes showed that most of them were apparently upregulated after Vibrio parahaemolyticus or white spot syndrome virus (WSSV) infection. One type Ib crustin-like gene, mainly expressed in the ovary, showed the highest expression levels before the gastrula stage and was hardly detected after the limb bud stage, suggesting that it was a maternal immune effector. Collectively, the present data revealed the molecular and functional diversity of crustins and their potential evolutionary routes in crustaceans.

Highlights

Antimicrobial peptides (AMPs) are key elements of the innate immune system
The mapping information of each gene can be found in the Supplementary Table S1
The present study identified 34 transcripts encoding full-length crustin-like genes from the shrimp L. vannamei. They were classified into six types based on their N-terminal regions, with two newly reported types and two new sub-types

Summary

Introduction

Antimicrobial peptides (AMPs) are key elements of the innate immune system. AMPs are widely present in all multicellular organisms and exhibit a broad spectrum of activities against bacteria, fungi, yeast, protozoa, and viruses [1]. As of March 2020, as many as 3175 AMPs have been reported in the Antimicrobial Peptide Database (http://aps.unmc.edu/AP/main.php). AMPs show tremendous sequence diversity, which suggests that organisms employ this mechanism to adapt to microbial challenges in different environments [2]. Various types of AMPs are effective components in the host innate immune system to protect them against pathogen infection. Especially decapods, different AMP families including penaeidins, anti-lipopolysaccharide factors, crustins, stylicins, etc., have been identified and characterized [3,4,5,6]

Methods

Results

Discussion

Conclusion