Synthetic collagen, protein microarrays and lipid bilayers – Sunday morning, #ACSSanFran

Published in Protocols & Methods

The “National Fresenius Award Symposium” celebrates researchers that have made amazing early career advances; this year the award went to Neal K. Devaraj, and this session was assembled in his honour.

The session started with a talk by David Chenowerth on making synthetic collagen. Collagen is a peptide triple helix made of peptide chains of the general form: [Gxx]3. His group has been doing experiments replacing carbon atoms with nitrogen – e.g. using aza-glycine instead of glycine in one (or more) of the repeating triplets Proline-Hydroxyproline-Glycine – which has remarkable effects on the stability of the resulting triple helices.

After a fascinating talk from Dale Poulter about exploiting the versatility of farnesyl transferase for the preparation of protein microarrays, there were three talks about lipid bilayers.

Steven Boxer spoke about recent work on tethered lipid bilayers – using a really clever approach using lipid-DNA conjugates with complementary DNA strands – which has been applied to looking at membrane fusion of enveloped viruses.

For imaging organelles, you could label either the membrane proteins or the lipids. An advantage of labelling the lipids is that there are many more lipid molecules than proteins in the membrane, so if you choose a photostable fluorophore that blinks spontaneously it should be possible to image for longer time periods before you get photobleaching. Alanna Schepartz spoke about work using an environmentally sensitive (fluorescesces more at low pH) fluorophore (Sir-Tz) to image things like Golgi and ER using STED.  The Supplementary Movies are remarkable both for the resolution, and for the length of time of the imaging experiment.

The last talk was by Neal Devaraj who spoke about his work on in situ synthesis membrane synthesis. So what does this mean? He creates clickable phospholipid precursors, sets up the reaction and watches how new lipid vesicles form over time. To solve the problem of catalyst dilution over time, they developed a really neat system for continual synthesis of a catalytic membrane.

Image taken from: 10.1073/pnas.1506704112, Hardy et al. (2015) PNAS 112  pp 8187-8192

They have also done some exciting work towards synthetic re-modelling of lipid bilayers using a reversible covalent coupling. Remarkably it is possible to see the formation of microdomains!

Image taken from: doi: 10.1073/pnas.1605541113, Brea et al. (2016) PNAS 113 pp 8589-8594

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