Newly identified type II crustin (SpCrus2) in Scylla paramamosain contains a distinct cysteine distribution pattern exhibiting broad antimicrobial activity
Newly identified type II crustin (SpCrus2) in Scylla paramamosain contains a distinct cysteine distribution pattern exhibiting broad antimicrobial activity
复制标题
拟青青蟹中新鉴定的 II 型结皮蛋白 (SpCrus2) 含有独特的半胱氨酸分布模式，表现出广泛的抗菌活性
DOI：
10.1016/j.dci.2018.01.021
复制
发表时间：
2018-07-01
影响因子：
2.9
通讯作者：
Li, Xin-Cang
中科院分区：
文献类型：
--
作者：
Wang, Hui;Zhang, Jing-Xiao;Li, Xin-Cang
Ⅱ型甲壳素是对虾中含量最丰富的甲壳素类型，具有显著的序列差异和广泛的抗菌活性。本研究的特点是一种新的II型crustin，SpCrus 2，在青蟹拟穴青蟹。SpCrus 2 cDNA序列长620 bp，开放阅读框为495 bp，编码164个氨基酸。在推导的蛋白质，一个17个氨基酸的信号肽，富含甘氨酸的疏水区（GRR），和富含半胱氨酸的区域（CRR）含有乳清酸性蛋白结构域进行了预测。SpCrus 2与虾中的大多数II型甲壳（IIa和IIb型甲壳）具有高度相似性，但具有与大多数甲壳不同的半胱氨酸残基的新分布模式。SpCrus 2和PlCrus 3具有高度的相似性和相同的半胱氨酸残基分布模式。因此，我们建议将其作为llc型结壳。SpCrus 2主要分布在鳃中，并且可以通过副溶血性弧菌或金黄色葡萄球菌攻击而上调。为了研究SpCrus 2的生物学功能和潜在的机制，SpCrus 2、GRR、CRR和CRR的突变体（CRR-M，半胱氨酸分布模式突变为大多数常规甲壳素中的半胱氨酸分布模式）都被过量表达和纯化。SpCrus 2 GRR本身作为富含甘氨酸的两亲性肽，对革兰氏阴性菌具有明显的抗菌活性，而CRR对革兰氏阳性菌具有较强的抗菌活性。GRR和CRR的抑菌活性均低于SpCrus 2的全蛋白，表明GRR和CRR协同发挥其潜在的抑菌功能。此外，CRR表现出比CRR-M稍强的抗微生物活性，这表明含有这种新的半胱氨酸分布模式的SpCrus 2可能表现出比大多数具有半胱氨酸残基的常规分布模式的II型甲壳更强的抗微生物活性。SpCrus 2可能的抗菌能力可能来自其微生物多糖结合和凝集活性。总体而言，这项研究的特点是第一个II型甲壳素在螃蟹，并提供了新的见解，了解序列和功能多样性的甲壳类动物及其免疫功能。(C)2018爱思唯尔有限公司版权所有。
Type II crustins are the most abundant type of crustins in shrimps that exhibit remarkable sequence diversities and broad antibacterial activities. This study characterized a novel type II crustin, SpCrus2, in the mud crab Scylla paramamosain. The SpCrus2 cDNA sequence is 620-bp long with a 495-bp open reading frame encoding a 164-amino acid protein. In the deduced protein, a 17-amino acid signal peptide, a glycine-rich hydrophobic region (GRR), and a cysteine-rich region (CRR) containing a whey acidic protein domain were predicted. SpCrus2 shares high similarity with most type II crustins (types Ila and Ilb crustins) in shrimps but has a novel distribution pattern of cysteine residues that is distinct from most crustins. SpCrus2 and PlCrus3 from Pacifastacus leniusculus share high similarity and the same distribution pattern of cysteine residues. Thus, we proposed them as type llc crustins. SpCrus2 is mainly distributed in the gills and can be up-regulated through Vibrio parahemolyticus or Staphylococcus aureus challenge. To investigate the biological functions of SpCrus2 and the underlying mechanisms, SpCrus2, GRR, CRR, and the mutant of CRR (CRR-M, the cysteine distribution pattern is mutated into that in most conventional crustins) were all overexpressed and purified. SpCrus2 GRR itself, as a glycine-rich amphiphilic peptide, exhibited evident antibacterial ability against Gram-negative bacteria, whereas CRR possessed potent antibacterial activity against Gram-positive bacteria. Either GRR or CRR exhibited weaker antibacterial activity than the whole protein of SpCrus2, indicating that GRR and CRR synergized to exert their potential antibacterial functions. In addition, CRR exhibited slightly stronger antimicrobial activity than CRR-M, suggesting that SpCrus2 containing this novel cysteine distribution pattern may exhibit stronger antimicrobial activity than most type II crustins with the conventional distribution pattern of cysteine residues. The likely antimicrobial ability of SpCrus2 may result from its microbial polysaccharide-binding and agglutination activities. Overall, this study characterized the first type II crustin in crabs and provided new insights into understanding the sequence and functional diversity of crustins and their immune functions in crustaceans. (C) 2018 Elsevier Ltd. All rights reserved.