October 1, 2000Acta Crystallographica Section D Biological Crystallography188 citationsOpen Access
Fitting atomic models into electron-microscopy maps
Structured PICO
P
Population
alphaviruses, rhinovirus-receptor interactions and poliovirus-receptor interactions
I
Intervention
Combining X-ray crystallographically determined atomic structures with cryo-electron microscopic three-dimensional images
O
Outcome
structural information accuracy
Combining X-ray crystallography with cryo-EM maps allows for highly accurate structural modeling of viral and receptor interactions.
Abstract
Combining X-ray crystallographically determined atomic structures of component domains or subunits with cryo-electron microscopic three-dimensional images at around 22 A resolution can produce structural information that is accurate to about 2.2 A resolution. In an initial step, it is necessary to determine accurately the absolute scale and absolute hand of the cryo-electron microscopy map, the former of which can be off by up to 5%. It is also necessary to determine the relative height of density by using a suitable scaling function. Difference maps can identify, for instance, sites of glycosylation, the position of which helps to fit the component structures into the EM density maps. Examples are given from the analysis of alphaviruses, rhinovirus-receptor interactions and poliovirus-receptor interactions.