文献类型：期刊文献

英文题名：HcN57, A Novel Unusual Acidic Silk-Like Matrix Protein from Hyriopsis cumingii, Participates in Framework Construction and Nacre Nucleation During Nacreous Layer Formation

作者：Jin, Can[1]; Wei, Fangmengjie[1]; Zhang, Jiayi[1]; Tan, Xiaoyang[1]; Fan, Taixia[1]; Luo, Wen[1]; Li, Jiale[2,3,4]

机构：[1] School of Life and Environmental Sciences, Shaoxing University, Shaoxing, China; [2] Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture and Rural Affairs, Shanghai Ocean University, Shanghai, 201306, China; [3] Shanghai Engineering Research Center of Aquaculture, Shanghai Ocean University, Shanghai, 201306, China; [4] Shanghai Collaborative Innovation Center of Aquatic Animal Breeding and Green Aquaculture, Shanghai Ocean University, Shanghai, 201306, China

年份：2024

卷号：26

期号：4

起止页码：716

外文期刊名：Marine Biotechnology

收录：EI(收录号：20242516287637)、Scopus(收录号：2-s2.0-85196277003)

语种：英文

外文关键词：Amino acids - Calcite - Calcium - Deposition - Ethylenediaminetetraacetic acid - Proteins

外文摘要：In the classic molecular model of nacreous layer formation, unusual acidic matrix proteins rich in aspartic acid (Asp) residues are essential for nacre nucleation due to their great affinity for binding calcium. However, the acidic matrix proteins discovered in the nacreous layer so far have been weakly acidic with a high proportion of glutamate. In the present study, several silk-like matrix proteins, including the novel matrix protein HcN57, were identified in the ethylenediaminetetraacetic acid-soluble extracts of the nacreous layer of Hyriopsis cumingii. HcN57 is a highly repetitive protein that consists of a high proportion of alanine (Ala, 34.4%), glycine (Gly, 22.5%), and serine (Ser, 11.4%). It forms poly Ala blocks, GlynX repeats, an Ala-Gly repeat, and a Ser-Ala-rich region, exhibiting significant similarity to silk proteins found in spider species. The expression of HcN57 was specifically located in the dorsal epithelial cells of the mantle pallium and mantle center. Notably, expression of HcN57 was relatively high during nacreous layer regeneration and pearl nacre deposition, suggesting HcN57 is a silk matrix protein in the nacreous layer. Importantly, HcN57 also contains a certain content of Asp residues, making it an unusual acidic matrix protein present in the nacreous layer. These Asp residues are mainly distributed in three large hydrophilic acidic regions, which showed inhibitory activity against aragonite deposition and morphological regulation of calcite in vitro. Moreover, HcN57-dsRNA injection resulted in failure of nacre nucleation in vivo. Taken together, our results show that HcN57 is a bifunctional silk protein with poly Ala blocks and Gly-rich regions that serve as space fillers within the chitinous framework to prevent crystallization at unnecessary nucleation sites and Asp-rich regions that create a calcium ion supersaturated microenvironment for nucleation in the center of nacre tablets. These observations contribute to a better understanding of the mechanism by which silk proteins regulate framework construction and nacre nucleation during nacreous layer formation. ? The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.