Structures of large T antigen at the origin of SV40 DNA replication by atomic force microscopy
| Autor: | Magdalena Bezanilla, Paul V. C. Hough, Paul K. Hansma, Iris A. Mastrangelo, Helen G. Hansma |
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| Rok vydání: | 1994 |
| Předmět: |
DNA Replication
Microscopy Electron Scanning Transmission 0303 health sciences Microscopy Molecular Structure Chemistry Protein Conformation 030302 biochemistry & molecular biology DNA replication Biophysics Uranyl acetate Simian virus 40 Random hexamer Biophysical Phenomena 03 medical and health sciences Crystallography chemistry.chemical_compound Protein structure Scanning transmission electron microscopy Molecule Antigens Viral Tumor DNA 030304 developmental biology Research Article |
| Zdroj: | Biophysical Journal. 66(2):293-298 |
| ISSN: | 0006-3495 |
| DOI: | 10.1016/s0006-3495(94)80800-8 |
| Popis: | For inorganic crystals such as calcite (CaCO3), Atomic Force Microscopy (AFM) has provided surface structure at atomic resolution (Ohnesorge and Binnig, 1993). As part of a broad effort to obtain high resolution for an individual protein or protein assembly (Binnig et al., 1986; Rugar and Hansma, 1990; Radmacher et al., 1992), we applied AFM to study the ATP-dependent double hexamer of SV40 large T antigen, which assembles around the viral origin of DNA replication. Multimeric mass has been determined in two-dimensional projected images by Scanning Transmission Electron Microscopy (STEM) (Mastrangelo et al., 1989). By AFM, if the DNA-protein preparation has been stained positively by uranyl acetate, the contour at the junction between hexamers is visible as a cleft, 2–4 nm deep. The cleft, whether determined as a fraction of height by AFM or as a fraction of mass thickness by STEM, is of comparable magnitude. On either side of the cleft, hexamers attain a maximum height of 13–16 nm. Monomers found in the absence of ATP show heights of 5–7 nm. Taken together, the z coordinates provide a surface profile of complete and partial replication assemblies consistent with the spatial distribution of recognition pentanucleotides on the DNA, and they contribute direct geometrical evidence for a ring-like hexamer structure. |
| Databáze: | OpenAIRE |
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