TY - JOUR
T1 - Prospects of electron cryotomography to visualize macromolecular complexes inside cellular compartments
T2 - Implications of crowding
AU - Grünewald, Kay
AU - Medalia, Ohad
AU - Gross, Ariane
AU - Steven, Alasdair C.
AU - Baumeister, Wolfgang
N1 - Funding Information:
We thank Dr Irina Gutsche for help with tomogram alignment and Dr Eva Kocsis for performing a symmetry detection analysis. This work was supported in part by Fellowships from the Alexander von Humboldt Stiftung (to A.C.S.), the Deutsche Forschungsgemeinschaft and the Max-Planck-Society (to K.G.), and the European Commission Marie Curie Individual Fellowship (to O.M.).
PY - 2002/12/1
Y1 - 2002/12/1
N2 - Electron cryotomography has unique potential for three-dimensional visualization of macromolecular complexes at work in their natural environment. This approach is based on reconstructing three-dimensional volumes from tilt series of electron micrographs of cells preserved in their native states by vitrification. Resolutions of 5-8 nm have already been achieved and the prospects for further improvement are good. Since many intracellular activities are conducted by complexes in the megadalton range with dimensions of 20-50 nm, current resolutions should suffice to identify many of them in tomograms. However, residual noise and the dense packing of cellular constituents hamper interpretation. Recently, tomographic data have been collected on vitrified eukaryotic cells (Medalia et al., Science (2002) in press). Their cytoplasm was found to be markedly less crowded than in the prokaryotes previously studied, in accord with differences in crowding between prokaryotic and eukaryotic cells documented by other (indirect) biophysical methods. The implications of this observation are twofold. First, complexes should be more easily identifiable in tomograms of eukaryotic cytoplasm. This applies both to recognizing known complexes and characterizing novel complexes. An example of the latter - a 5-fold symmetric particle is - given. Second, electron cryotomography offers an incisive probe to examine crowding in different cellular compartments.
AB - Electron cryotomography has unique potential for three-dimensional visualization of macromolecular complexes at work in their natural environment. This approach is based on reconstructing three-dimensional volumes from tilt series of electron micrographs of cells preserved in their native states by vitrification. Resolutions of 5-8 nm have already been achieved and the prospects for further improvement are good. Since many intracellular activities are conducted by complexes in the megadalton range with dimensions of 20-50 nm, current resolutions should suffice to identify many of them in tomograms. However, residual noise and the dense packing of cellular constituents hamper interpretation. Recently, tomographic data have been collected on vitrified eukaryotic cells (Medalia et al., Science (2002) in press). Their cytoplasm was found to be markedly less crowded than in the prokaryotes previously studied, in accord with differences in crowding between prokaryotic and eukaryotic cells documented by other (indirect) biophysical methods. The implications of this observation are twofold. First, complexes should be more easily identifiable in tomograms of eukaryotic cytoplasm. This applies both to recognizing known complexes and characterizing novel complexes. An example of the latter - a 5-fold symmetric particle is - given. Second, electron cryotomography offers an incisive probe to examine crowding in different cellular compartments.
KW - Electron tomography
KW - Eukaryote/prokaryote distinction
KW - Macromolecular crowding
KW - Vitrification
UR - http://www.scopus.com/inward/record.url?scp=0037438344&partnerID=8YFLogxK
U2 - 10.1016/S0301-4622(02)00307-1
DO - 10.1016/S0301-4622(02)00307-1
M3 - Article
AN - SCOPUS:0037438344
SN - 0301-4622
VL - 100
SP - 577
EP - 591
JO - Biophysical Chemistry
JF - Biophysical Chemistry
IS - 1-3
ER -