Membrane proteins: advanced level problem solving without “one size fits all” solution
Despite the recent advances in structural biology, membrane proteins remained notoriously difficult to study. These proteins are crucial to all forms of life, and are involved in essential cellular and physiological processes. At LINXS, two workshops on how to overcome the challenges of membrane protein structure determination will be organised this year.
Erika Tóth is a postdoctoral fellow at Pheromone Group, Functional Zoology at Lund University, and member of the working group on membrane proteins, under the theme Integrative Structural Biology.
– Problem-solving where there is no universal solution. This is how I would describe working with membrane protein structural biology. We want to discuss benefits and disadvantages of different expression systems and methodological pipelines, says Erika Tóth, postdoctoral fellow at Functional Zoology at Lund University, and member of the working group on membrane proteins.
Membranes are difficult to study
She explains that membrane proteins are difficult to study for a number of reasons. Their surface is partially hydrophobic so they can only be extracted from the cell membrane with detergents. They are also often flexible and unstable, something which leads to challenges at every step - including expression, solubilisation, purification, crystallisation, data collection and structure solution. Around 30 percent of all proteins are membrane proteins and over 50 percent of them are drug targets. The last fifteen years have witnessed a rapid expansion in technological and methodological developments that has resulted in more than 1000 unique membrane protein structures, however many bottlenecks remain to be eliminated.
– The moment you disrupt the cell membrane and extract the protein from its natural environment is crucial. You need to use the right detergent(s) to incorporate the protein in micelles, otherwise the protein loses its shape and is no longer active. Using advanced artificial scaffolds can provide a more biologically relevant environment to maintain functional membrane proteins.
Three areas in focus for workshop
In the first workshop the membrane protein working group will focus specifically on three areas: expression systems, sample preparation and quality control. The aim is to provide expert overview on membrane protein production for crystallography techniques, output/structural resolution, including scattering techniques, neutron structures and cryogenic electron microscopy (cryo-EM).
– We invite people to introduce their best practices in sample preparation and quality control with respect to research materials and methods, in order to provide greater knowledge and knowledge transfer on how best to deal with the challenges.
- There are so many different paths you can take, and a lot of trial and error needed to get things right. One has to remember that it usually takes several years to crystalize a membrane protein, says Erika Tóth.
Both early career and senior researchers welcome
The working group hopes to engage the attendance from PhD students and post-docs from a range of disciplines, as well as more senior researchers. The membrane protein research field is growing, and so is the need to build a community that can share knowledge and exchange ideas. This will contribute towards a greater ability to make the most out of the state-of-the-art facilities in our neighborhood (i.e. MaxIV and ESS) facilitating design and implementation of research questions previously unobtainable.
– Take me for an example. I am not a structural biologist but I need more structural knowledge to progress in my research.
Her work focuses on genetically modifying desaturase enzymes to produce tailor made insect sex pheromones as an alternative solution to replace the conventional, highly toxic insecticides.
– The functional tuning of the target enzymes is so subtle. If you can modify the enzyme, and synthesize the needed pheromone compound in cell factories, then you can provide species-specific and sustainable solution against pest insects.
Interest to study things in close detail
She has always had an interest in seeing things close up, to study them in detail. This interest is what brought her to do research.
– I like to consider it as a puzzle, the more knowledge you have, the bigger picture you can see. I started with microbiology and biotechnology, now my main research field is molecular biology. I got into structural biology to understand how modifying the coding DNA of my target membrane protein will affect its structure.
– We hope that this workshop will make membrane protein structural biology more accessible to a broader community of scientists. We coalesce local and international specialists and MaxIV/ESS end-users to support those who have interest in structural biology questions related to the membrane proteins that they do research on, she concludes.
The workshop: Structural Resolution of Membrane Protein: From Expression to Sample Preparation, will take place from 25 - 26 May.