What’s in a work space? Lori Passmore and her images of science
Dr Lori Passmore is head of the Mechanisms of Macromolecular Machines group in the Structural Studies Division at the MRC Laboratory of Molecular Biology (LMB). She showed Isabel Baker around her shiny new office where she approaches biological questions using structural biology methods.
These coasters were made by a friend of mine who does glass fusing. She’s put some actual electron microscopy (EM) grids, which we use to image proteins, inside the glass. Each grid is 3mm in diameter, made of a disc of metal such as copper or gold, often with a layer of carbon on top. To use these grids in the lab, we pipette a few microlitres of protein in solution on top and remove the excess solution, leaving a thin layer containing the protein. For cryo-EM – where we freeze the samples at liquid nitrogen temperature to preserve them in the vacuum of the microscope – the carbon has holes in it. When you freeze the grid, the protein molecules are trapped in ice suspended across the holes. We then image the protein, in the suspension of ice across the grid.
We purify large protein complexes and image them in the microscope. I think it’s amazing to see individual protein molecules, only 20 nanometres across! Until two years ago we always took EM images on film. I use this light box and magnifying glass to look at film images. Each of the spots is an individual protein complex. Now, new electron detectors mean we don’t have to use film any more, but occasionally I still look at them. It’s a fascinating time for EM; in the space of two years it’s been revolutionised.
Nobel chocolate coin
These are chocolate coins from a Nobel Prize dinner. In 2009, just after I was a postdoc with Venki Ramakrishnan, he won the Nobel Prize for his work on the ribosome. Almost everyone who had worked with him on ribosomes went to Stockholm. We attended the Nobel Prize lecture, celebrated with Venki and got to spend a few days together. It was an exciting time. Venki’s lab has always worked really closely together as a team. The reunion in Stockholm was a great time to catch up.
Picture of DNA
I have two daughters, aged six and two. This is a picture drawn by my six-year-old; she drew what she thought DNA might look like. She loves science, talking about it and asking what I’m working on. I just did a demonstration using paper chromatography with her class at school which was a lot of fun.
This is a piece of copper foil with a one carbon atom-thick layer of graphene on top. We’ve recently started using graphene to help image proteins in EM. When imaging thin layers of solution, proteins are attracted to the air-water interface, which damages them. To prevent damage, we put a layer of carbon on the grid for proteins to stick to. However carbon can produce lots of background signal. The proteins also move in the electron beam resulting in blurry EM images. Graphene is a good alternative: it’s invisible at EM resolutions and helps reduce movement. My postdoc, Chris Russo, has developed a way to produce graphene and make it hydrophilic, so that proteins can stick to
it, improving the quality of EM images.†
I cycle into the lab every day as I live not too far away. I take my time, I don’t cycle fast and I have a bit of time to think about my day (and science) before I get into the lab.
I have lots of books including all of my lab notebooks. They’re from different topics and time periods, even some of my PhD notes are up there. I still do experiments myself and I really love being in the lab with my group, not just sitting at my desk. My lab focuses on the large protein complexes that act on messenger RNAs (mRNA), either to add or remove their polyA tails. This is important for their translation into protein and for Nobel chocolate coin mRNA stability.
A version of this article was published in the Summer 2014 issue of Network.