Electron microscopic study of yeast RNA polymerase A: analysis of single molecular images.
The structural features of the yeast DNA-dependent RNA polymerase A (I) were examined by Scanning Transmission Electron Microscopy. The enzyme was absorbed in its monomeric form and negatively stained prior to digital image acquisition at low dose. The signal to noise ratio of single particle images was improved through averaging of a large number of previously aligned and partitioned images. Six classes of images were obtained reproducibly which corresponded to different projections of the enzyme. The enzyme structure was characterized by its presence of two curved arms which defined a longitudinal cleft. By analogy with the Escherichia coli enzyme, these arms could correspond to the two large subunits A135 and A190.
Laboratoire de Génétique Moléculaire des Eucaryotes, Strasbourg, France.
P
P
Schultz
P
P
Nobelis
P
P
Colin
M
M
Louys
J
J
Huet
A
A
Sentenac
P
P
Oudet
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005583:Fourier Analysis; D008855:Microscopy, Electron, Scanning; D015394:Molecular Structure; D012318:RNA Polymerase I / Q000145:classification
D012318:RNA Polymerase I