{"title":"大肠杆菌中表达的人唾液凝集素清道夫受体富半胱氨酸结构域的重折叠、结晶和晶体结构分析。","authors":"Changyu Zhang, Peng Lu, Sibo Wei, Chaoyue Hu, Mitsuko Miyoshi, Ken Okamoto, Hideaki Itoh, Suguru Okuda, Michio Suzuki, Hiroshi Kawakami, Koji Nagata","doi":"10.1007/s10930-023-10173-x","DOIUrl":null,"url":null,"abstract":"<div><p>Scavenger receptors are a protein superfamily that typically consists of one or more repeats of the scavenger receptor cysteine-rich structural domain (SRCRD), which is an ancient and highly conserved protein module. The expression and purification of eukaryotic proteins containing multiple disulfide bonds has always been challenging. The expression systems that are commonly used to express SRCRD proteins mainly consist of eukaryotic protein expression systems. Herein, we established a high-level expression strategy of a Type B SRCRD unit from human salivary agglutinin using the <i>Escherichia coli</i> expression system, followed by a refolding and purification process. The untagged recombinant SRCRD was expressed in <i>E. coli</i> using the pET-32a vector, which was followed by a refolding process using the GSH/GSSG redox system. The SRCRD expressed in <i>E. coli</i> SHuffle T7 showed better solubility after refolding than that expressed in <i>E. coli</i> BL21(DE3), suggesting the importance of the disulfide bond content prior to refolding. The quality of the refolded protein was finally assessed using crystallization and crystal structure analysis. As proteins refolded from inclusion bodies exhibit a high crystal quality and reproducibility, this method is considered a reliable strategy for SRCRD protein expression and purification. To further confirm the structural integrity of the refolded SRCRD protein, the purified protein was subjected to crystallization using sitting-drop vapor diffusion method. The obtained crystals of SRCRD diffracted X-rays to a resolution of 1.47 Å. The solved crystal structure appeared to be highly conserved, with four disulfide bonds appropriately formed. The surface charge distribution of homologous SRCRD proteins indicates that the negatively charged region at the surface is associated with their calcium-dependent ligand recognition. These results suggest that a high-quality SRCRD protein expressed by <i>E. coli</i> SHuffle T7 can be successfully folded and purified, providing new options for the expression of members of the scavenger receptor superfamily.</p></div>","PeriodicalId":793,"journal":{"name":"The Protein Journal","volume":null,"pages":null},"PeriodicalIF":1.9000,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11058800/pdf/","citationCount":"0","resultStr":"{\"title\":\"Refolding, Crystallization, and Crystal Structure Analysis of a Scavenger Receptor Cysteine-Rich Domain of Human Salivary Agglutinin Expressed in Escherichia coli\",\"authors\":\"Changyu Zhang, Peng Lu, Sibo Wei, Chaoyue Hu, Mitsuko Miyoshi, Ken Okamoto, Hideaki Itoh, Suguru Okuda, Michio Suzuki, Hiroshi Kawakami, Koji Nagata\",\"doi\":\"10.1007/s10930-023-10173-x\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Scavenger receptors are a protein superfamily that typically consists of one or more repeats of the scavenger receptor cysteine-rich structural domain (SRCRD), which is an ancient and highly conserved protein module. The expression and purification of eukaryotic proteins containing multiple disulfide bonds has always been challenging. The expression systems that are commonly used to express SRCRD proteins mainly consist of eukaryotic protein expression systems. Herein, we established a high-level expression strategy of a Type B SRCRD unit from human salivary agglutinin using the <i>Escherichia coli</i> expression system, followed by a refolding and purification process. The untagged recombinant SRCRD was expressed in <i>E. coli</i> using the pET-32a vector, which was followed by a refolding process using the GSH/GSSG redox system. The SRCRD expressed in <i>E. coli</i> SHuffle T7 showed better solubility after refolding than that expressed in <i>E. coli</i> BL21(DE3), suggesting the importance of the disulfide bond content prior to refolding. The quality of the refolded protein was finally assessed using crystallization and crystal structure analysis. As proteins refolded from inclusion bodies exhibit a high crystal quality and reproducibility, this method is considered a reliable strategy for SRCRD protein expression and purification. To further confirm the structural integrity of the refolded SRCRD protein, the purified protein was subjected to crystallization using sitting-drop vapor diffusion method. The obtained crystals of SRCRD diffracted X-rays to a resolution of 1.47 Å. The solved crystal structure appeared to be highly conserved, with four disulfide bonds appropriately formed. The surface charge distribution of homologous SRCRD proteins indicates that the negatively charged region at the surface is associated with their calcium-dependent ligand recognition. These results suggest that a high-quality SRCRD protein expressed by <i>E. coli</i> SHuffle T7 can be successfully folded and purified, providing new options for the expression of members of the scavenger receptor superfamily.</p></div>\",\"PeriodicalId\":793,\"journal\":{\"name\":\"The Protein Journal\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.9000,\"publicationDate\":\"2024-01-24\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11058800/pdf/\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"The Protein Journal\",\"FirstCategoryId\":\"2\",\"ListUrlMain\":\"https://link.springer.com/article/10.1007/s10930-023-10173-x\",\"RegionNum\":4,\"RegionCategory\":\"生物学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q4\",\"JCRName\":\"BIOCHEMISTRY & MOLECULAR BIOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Protein Journal","FirstCategoryId":"2","ListUrlMain":"https://link.springer.com/article/10.1007/s10930-023-10173-x","RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
Refolding, Crystallization, and Crystal Structure Analysis of a Scavenger Receptor Cysteine-Rich Domain of Human Salivary Agglutinin Expressed in Escherichia coli
Scavenger receptors are a protein superfamily that typically consists of one or more repeats of the scavenger receptor cysteine-rich structural domain (SRCRD), which is an ancient and highly conserved protein module. The expression and purification of eukaryotic proteins containing multiple disulfide bonds has always been challenging. The expression systems that are commonly used to express SRCRD proteins mainly consist of eukaryotic protein expression systems. Herein, we established a high-level expression strategy of a Type B SRCRD unit from human salivary agglutinin using the Escherichia coli expression system, followed by a refolding and purification process. The untagged recombinant SRCRD was expressed in E. coli using the pET-32a vector, which was followed by a refolding process using the GSH/GSSG redox system. The SRCRD expressed in E. coli SHuffle T7 showed better solubility after refolding than that expressed in E. coli BL21(DE3), suggesting the importance of the disulfide bond content prior to refolding. The quality of the refolded protein was finally assessed using crystallization and crystal structure analysis. As proteins refolded from inclusion bodies exhibit a high crystal quality and reproducibility, this method is considered a reliable strategy for SRCRD protein expression and purification. To further confirm the structural integrity of the refolded SRCRD protein, the purified protein was subjected to crystallization using sitting-drop vapor diffusion method. The obtained crystals of SRCRD diffracted X-rays to a resolution of 1.47 Å. The solved crystal structure appeared to be highly conserved, with four disulfide bonds appropriately formed. The surface charge distribution of homologous SRCRD proteins indicates that the negatively charged region at the surface is associated with their calcium-dependent ligand recognition. These results suggest that a high-quality SRCRD protein expressed by E. coli SHuffle T7 can be successfully folded and purified, providing new options for the expression of members of the scavenger receptor superfamily.
期刊介绍:
The Protein Journal (formerly the Journal of Protein Chemistry) publishes original research work on all aspects of proteins and peptides. These include studies concerned with covalent or three-dimensional structure determination (X-ray, NMR, cryoEM, EPR/ESR, optical methods, etc.), computational aspects of protein structure and function, protein folding and misfolding, assembly, genetics, evolution, proteomics, molecular biology, protein engineering, protein nanotechnology, protein purification and analysis and peptide synthesis, as well as the elucidation and interpretation of the molecular bases of biological activities of proteins and peptides. We accept original research papers, reviews, mini-reviews, hypotheses, opinion papers, and letters to the editor.