1
|
Jensen IS, Yuan J, He J, Lin L, Sander B, Golas MM. The FlpTRAP system for purification of specific, endogenous chromatin regions. Anal Biochem 2019; 587:113418. [PMID: 31520595 DOI: 10.1016/j.ab.2019.113418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 09/07/2019] [Accepted: 09/08/2019] [Indexed: 10/26/2022]
Abstract
The repressor element 1-silencing transcription factor/neuron-restrictive silencer factor (REST/NRSF) binds to repressor element 1/neuron-restrictive silencer element (RE1/NRSE) sites in the genome and recruits effector proteins to repress its target genes. Here, we developed the FlpTRAP system to isolate endogenously assembled DNA-protein complexes such as the REST/NRSF complex. In the FlpTRAP system, we take advantage of the step-arrest variant of the Flp recombinase, FlpH305L, which, in the presence of Flp recognition target (FRT) DNA, accumulates as FRT DNA-protein adduct. The FlpTRAP system consists of three elements: (i) FlpH305L-containing cell extracts or isolates, (ii) a cell line engineered to harbor the DNA motif of interest flanked by FRT sites, and (iii) affinity selection steps to isolate the target chromatin. Specifically, 3×FLAG-tagged FlpH305L was expressed in insect cell cultures infected with baculovirus, and cell lysates were prepared. The lysate was used to capture the FRT-SNAP25 RE1/NRSE-FRT chromatin from a human medulloblastoma cell line, and the target RE1/NRSE chromatin was isolated by anti-FLAG immunoaffinity chromatography. Using electrophoretic mobility shift assays (EMSAs) and chromatin immunopurification (ChIP), we show that FlpH305L recognized and bound to the FRT sites. Overall, we suggest the FlpTRAP system as a tool to purify endogenous, specific chromatin loci from eukaryotic cells.
Collapse
Affiliation(s)
- Ida S Jensen
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, Building 1233, 8000, Aarhus C, Denmark
| | - Juan Yuan
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, Building 1233, 8000, Aarhus C, Denmark
| | - Jin He
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, Building 1233, 8000, Aarhus C, Denmark
| | - Lin Lin
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, Building 1233, 8000, Aarhus C, Denmark
| | - Bjoern Sander
- Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Wilhelm Meyers Allé 3, Building 1233, 8000, Aarhus C, Denmark
| | - Monika M Golas
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, Building 1233, 8000, Aarhus C, Denmark.
| |
Collapse
|
2
|
Le LTM, Nyengaard JR, Golas MM, Sander B. Vectors for Expression of Signal Peptide-Dependent Proteins in Baculovirus/Insect Cell Systems and Their Application to Expression and Purification of the High-Affinity Immunoglobulin Gamma Fc Receptor I in Complex with Its Gamma Chain. Mol Biotechnol 2018; 60:31-40. [PMID: 29143175 DOI: 10.1007/s12033-017-0041-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Integral membrane proteins play a central role in various cellular functions and are important therapeutic targets. However, technical challenges in the overexpression and purification of membrane proteins often represent a limiting factor for biochemical and structural studies. Here, we constructed a set of vectors, derivatives of MultiBac vectors that can be used to express proteins with a cleavable N-terminal signal peptide in insect cells. We propose these vectors for expression of type I membrane proteins and other secretory pathway proteins that require the signal recognition particle for translocation to the endoplasmic reticulum (ER). The vectors code for N-terminal and C-terminal affinity tags including 3 × FLAG and Twin-Strep, which represent tags compatible with efficient translocation to the ER as well as with purification under mild conditions that preserve protein structure and function. As a model, we used our system to express and purify the engineered high-affinity immunoglobulin gamma Fc receptor I (CD64) in complex with its gamma subunit (γ-chain). We demonstrate that CD64 expressed in complex with the γ-chain is functional in immunoglobulin G (IgG) binding. The sedimentation of CD64 in complex with IgG suggests individual CD64/IgG complexes in addition to formation of high-molecular weight complexes. In summary, our vectors can be used as a tool for expression of membrane proteins, other secretory pathway proteins and their protein complexes.
Collapse
Affiliation(s)
- Le T M Le
- Stereology and EM Laboratory, Department of Clinical Medicine, Aarhus University, 8000, Aarhus C, Denmark
| | - Jens R Nyengaard
- Stereology and EM Laboratory, Department of Clinical Medicine, Aarhus University, 8000, Aarhus C, Denmark
- Core Center for Molecular Morphology, Department of Clinical Medicine, Aarhus University Hospital, 8000, Aarhus C, Denmark
- Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, 8000, Aarhus C, Denmark
| | - Monika M Golas
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 3, Building 1233/1234, 8000, Aarhus C, Denmark
- Department of Human Genetics, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Bjoern Sander
- Stereology and EM Laboratory, Department of Clinical Medicine, Aarhus University, 8000, Aarhus C, Denmark.
- Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, 8000, Aarhus C, Denmark.
- Institute of Pathology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
| |
Collapse
|
3
|
Identification of antigenic epitopes of monoclonal antibodies against the VP2 protein of the 25 serotype of bluetongue virus. Vet Microbiol 2018; 219:136-143. [DOI: 10.1016/j.vetmic.2018.04.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/02/2018] [Accepted: 04/05/2018] [Indexed: 11/21/2022]
|