Structural analysis of macromolecules using Cryo electron microscopy
Topic Editor: Professor Elena V Orlova
Crystallography, Institute for Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, Bloomsbury LONDON WC1E 7HX,UK;
Invitation to submit an original research article, opinion paper or review article for a special issue of AIMS Biophysics
Cryo electron microscopy has become a powerful tool in structural biology that allows visualisation of biological objects ranging from bio macromolecules of ~ 150-200 kDa to organelles and cells. This huge variety of sizes and complexity of bio complexes has led to three main approaches for their study: electron crystallography to analyses thin crystals, single particle analysis, and electron tomography. There have been a number of technical advances such as improvement of sources of electrons, making them more coherent and brighter, development methods of sample preparations keeping complexes in hydrated state, and preparation of cell sections of significantly thinner using focused beam milling. Other achievements of the last decade are related to development specialized systems for recording images in electron microscopes: the direct electron detectors. The new detectors have a better representation of high resolution information. These advances lead to further development of software for processing, methods of refinement of structures and their interpretation.
Electron crystallography needs two-dimensional crystals. This is a high-resolution technique and it was recently demonstrated that an atomic resolution can be attained. Single-particle analysis is particularly suited for structural studies of macromolecular complexes from ~ 200 kDa to mega Dalton complexes. During the last three years structures obtained by electron microscopy at the atomic level of resolution became a practical reality: asymmetrical complexes like mitochondrial ribosomes, a potassium channel, rod-shaped helical viruses and icosahedral viruses we analysed at the level 3.5-4.5 Å. Electron tomography is used to study non-repetitive large formations like cells or their components. That opens the road to study biological complexes in vivo at a nanometer resolution.
Cryo electron microscopy provides a unique basis for hybridisation of completely different approaches like biochemistry, mass spectroscopy and X-ray crystallography and integration of these results with native sub-cellular structural information. A combination of cryo electron tomographic imaging with ‘single particle’ approaches, fluorescence microscopy and X-ray microscopy/tomography (correlative microscopy) gives us an opportunity to reveal functioning of living processes at a molecular level. In the light of the modern state of achievements it would be useful to highlight the following aspects of cryo electron microscopy:
1. Advances in direct detectors
2. Automated data collection in EM
3. Best results in single particle structural analysis
a. Asymmetrical ribosome
b. Helical structures
c. Icosahedral structures
d. 2D crystals
4. Low resolution and biology
5. Interpretation of EM maps-> fittings and tracing of polypeptide chains.
6. Structure-function of bio-complexes.
Instruction for Authors : http://aimspress.com/news/89.html
Submission due date: 15 February 2015.