Three-dimensional reconstruction of helical polymers.
The field of three-dimensional electron microscopy began more than 45years ago with a reconstruction of a helical phage tail, and helical polymers continue to be important objects for three-dimensional reconstruction due to the centrality of helical protein and nucleoprotein polymers in all aspects of biology. We are now witnessing a fundamental revolution in this area, made possible by direct electron detectors, which has led to near-atomic resolution for a number of important helical structures. Most importantly, the possibility of achieving such resolution routinely for a vast number of helical samples is within our reach. One of the main problems in helical reconstruction, ambiguities in assigning the helical symmetry, is overcome when one reaches a resolution where secondary structure is clearly visible. However, obstacles still exist due to the intrinsic variability within many helical filaments.
Department of Biochemistry and Molecular Genetics, University of Virginia, Box 800733, Charlottesville, VA 22908, USA. Electronic address: egelman@virginia.edu.
Edward H
EH
Egelman
D001435:Bacteriophages / Q000648:ultrastructure; D008854:Microscopy, Electron / Q000379:methods*; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*
D011108:Polymers
Direct electron detectors; Helical polymers; Variable twist