Published: July 17th, 2018
This protocol describes a calibration-free approach for quantifying protein homo-oligomerization in vitro based on fluorescence fluctuation spectroscopy using commercial light scanning microscopy. The correct acquisition settings and analysis methods are shown.
Number and brightness is a calibration-free fluorescence fluctuation spectroscopy (FFS) technique for detecting protein homo-oligomerization. It can be employed using a conventional confocal microscope equipped with digital detectors. A protocol for the use of the technique in vitro is shown by means of a use case where number and brightness can be seen to accurately quantify the oligomeric state of mVenus-labelled FKBP12F36V before and after the addition of the dimerizing drug AP20187. The importance of using the correct microscope acquisition parameters and the correct data preprocessing and analysis methods are discussed. In particular, the importance of the choice of photobleaching correction is stressed. This inexpensive method can be employed to study protein-protein interactions in many biological contexts.
Protein-protein Interactions In Vitro
Traditionally, crystallography and nuclear magnetic resonance experiments combined with cryo-electron microscopy (cryoEM) are the technologies chosen to accurately describe the three-dimensional architecture of proteins and to infer their function by scrutinizing their high resolution structural details. Proteins, however, are not static structures and can undergo a variety of conformational changes and vibrations in time and space. This is why structural information from crystallographic or CryoEM data needs to be complemented with other techniques (<....
1. FKBP12 F36V -mVenus Purification
Detrending and monomeric brightness
Once the data has been acquired, one can start the brightness calculations to determine the oligomeric state of the protein of interest in the solution. Even if the effect of bleaching in solution may not be as drastic as it can be in vivo, the intensity trace will still probably not have stationary mean, possibly due to photophysical effects related to the fluorophor.......
N&B is a technique to detect multimerization using commercial light scanning confocal microscopes equipped with digital detectors. This approach is quite attractive compared to single point FCS, FCCS, and smFRET because it is calibration free and the brightness calculation is straightforward and concentration independent6. It is of major importance, however, to correct for bleaching and long-term intensity fluctuations before performing brightness calculations9; a sligh.......
This work has been supported by Wellcome Trust grant 105278/Z/14/2 to R.N. The Wellcome Trust Centre for Human Genetics is funded by Wellcome Trust Core Award 203852/Z/16/2. Work in the C.S. group is supported by Cancer Research UK (C20724/A14414), and the European Research Council under the European Union's Horizon 2020 Research and Innovation Programme Grant 647278.....
|RosettaTM (DE3) pLysS cells
|PubChem Substance ID 329824407
|PubChem Substance ID: 24892250
|LB starter culture
|PubChem Substance ID 329815691
|EDTA-free protease inhibitors
|S200 16/60 column
|Glass bottom 8 well observation dish
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