Research progress of proximity labeling technology based on biotin ligase in proteomics / 中国药科大学学报

@#Proximity-dependent biotinylation (PDB) uses biotin ligase fused to the protein of interest to biotinylate adjacent proteins, purify them with streptavidin beads, and then identify the biotinylated protein by mass spectrometry.This technology can be used to detect transient and/or low affinity interactions, provide a chance to learn more about membrane-less organelles and other subcellular structures that cannot be easily isolated or purified, and fill the gap in traditional methods.This article summarizes the technological development and application of PDB in recent years.

Surface interactions between two of the main periodontal pathogens: Porphyromonas gingivalis and Tannerella forsythia

PURPOSE: Porphyromonas gingivalis and Tannerella forsythia have been implicated as the major etiologic agents of periodontal disease. These two bacteria are frequently isolated together from the periodontal lesion, and it has been suggested that their interaction may increase each one's virulence potential. The purpose of this study was to identify proteins on the surface of these organisms that are involved in interbacterial binding. METHODS: Biotin labeling of surface proteins of P. gingivalis and T. forsythia and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was performed to identify surface proteins involved in the coaggregating activity between P. gingivalis and T. forsythia. RESULTS: It was found that three major T. forsythia proteins sized 161, 100, and 62 kDa were involved in binding to P. gingivalis, and P. gingivalis proteins sized 35, 32, and 26 kDa were involved in binding to T. forsythia cells. CONCLUSIONS: LC-MS/MS analysis identified one T. forsythia surface protein (TonB-linked outer membrane protein) involved in interbacterial binding to P. gingivalis. However, the nature of other T. forsythia and P. gingivalis surface proteins identified by biotin labeling could not be determined. Further analysis of these proteins will help elucidate the molecular mechanisms that mediate coaggregation between P. gingivalis and T. forsythia.

Site-specific biotinylation of EGFP with double biotin molecules based on Avi-tag technology / 中国免疫学杂志

Objective:To prepare the site-specific biotinylation of enhanced green fluorescence protein with double biotin molecules using Avi-tag technology.Methods:The EGFP gene was prepared by PCR and cloned into pdi-Avitag resulting the vector pEGFP-( Avitag) 2.The fusion protein EGFP-( Avitag ) 2 was expressed in E.coli DH5αand purified by employing IMAC.The site-specific biotinylation was implemented by BirA enzyme in vitro, and then was identified by competitive ELISA and Western blot.Results:The recombinant prokaryotic expression vector pEGFP-(Avitag)2 was correctly constructed,and EGFP-(Avitag)2 fusion was successfully expressed in E.coli DH5α.The results of competitive ELISA and Western blot showed that the EGFP-( Avitag) 2 could be site-specific biotinylation with double biotin molecules based on Avi-tag technology.Conclusion: The site-specific biotinylation of EGFP with double biotin molecules is successfully prepared,and we anticipate that can be used for BAS to improve the sensitivity and specificity of immunosensors.

Expression,Immobilization and Application of Biotinylated ATP Sulfurylase / 生物化学与生物物理进展

The modern large-scale pyrosequencing technology is a revolution of DNA sequencing.One of the key points in this technology is to get an ATP sulfurylase immobilized on the surface of magnetic beads and with a high activity.Biotinylated ATP sulfurylase can be immobilized on magnetic beads coated with streptavidin through the specific conjunction between biotin and streptavidin, but using chemical modification method to biotinylate ATPS will affect the activity of the enzyme.ATP sulfurylase fused with the carboxyl terminal 87 residues of Escherichia coli biotin carboxyl carrier protein(BCCP87) was expressed in E.coli using fusion expression strategy.Results from Western blot analysis and SDS-PAGE analysis showed that the fusion protein could be biotinylated in vivo, and the molecular mass of the fusion protein was about 64 ku.The biotinylated ATP sulfurylase could be immobilized on the surface of magnetic beads coated with strepavidin, and the immobilized ATPS could be used for quantification of PPi and pyrosequencing.An effective enzyme for the large-scale chip-based pyrosequencing system was supplied.

MR imaging of nude mouse bearing human hepatocellular carcinoma by using two-step pretargeting strategy / 中华放射学杂志

Objective To improve the sensitivity of MR molecular imaging by using targeting and magnifying effects of biotin-avidin system (BAS). Methods After preparing biotinylated monoclonal antibody HAb18, the number of biotin molecules coupled to each antibody and the binding capacity of biotinylated antibody were determined. Two-step pretargeting tumor imaging was first achieved by intravenously injecting biotinylated monoclonal antibody HAb18 into 8 BALB/c nude mice bearing QGY-7723 tumor cells line. 24 h later, Gd-DTAP-streptavidin (Gd-DTPA-SA) was injected. Gd-DTPA-HAb18 and Gd-DTPA were respectively injected intravenously into the other 12 tumor-bearing mice as contrast groups. MR imaging was performed before and 10, 30, 60 min, 3, 6, 12, 24 h, and 48 h after injection of MR contrast agents. All images were obtained using SE T_1-weighted imaging sequence. After MR imaging, enhancement time course of three different groups was determined by using enhancement data measured in the region of interest in the tumor. Enhancement ratio and contrast-to-noise of tumor were also calculated. Results The average number of biotin conjugated with each monoclonal antibody molecular was 20. And the immunoactivity of biotinylated antibody was 91%. In two-step pretargeting strategy, SI of tumor increased slowly and reached the maximum value at 6 h after injection of Gd-DTPA-SA, enhancement ratio and CNR of tumor had significant difference with other two enhancement methods. The enhancing effect of tumor was still perceptible even after 48 h. When using Gd-DTPA-HAb18, the tumor enhancement pattern was slow and slight. Even at 24 h after injection of Gd-DTPA-HAb18, enhancement ratio of tumor was 13.5%. After Gd-DTPA was injected, signal intensity of tumor increased rapidly, and reached the maximum value at 30 min after injection of Gd-DTPA, and then decreased rapidly. Conclusion Two-step pretargeting strategy based on BAS has specific and signal magnifying effects in tumor MR imaging. It can increase the number of gadolinium that bind to the tumor and provide new approach to MR molecular imaging.