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The bacteriophage φ29 head–tail connector imaged at high resolution with the atomic force microscope in buffer solution
Author(s) -
Müller Daniel J.,
Engel Andreas,
Carrascosa José L.,
Vélez Marisela
Publication year - 1997
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/16.10.2547
Subject(s) - biology , buffer (optical fiber) , resolution (logic) , bacteriophage , atomic force microscopy , head (geology) , biophysics , microscope , anatomy , optics , materials science , escherichia coli , physics , biochemistry , nanotechnology , telecommunications , paleontology , artificial intelligence , computer science , gene
The surfaces of two‐ and three‐dimensional φ29 connector crystals were imaged in buffer solution by atomic force microscopy (AFM). Both topographies show a rectangular unit cell with dimensions of 16.5 nm×16.5 nm. High resolution images of connectors from the two‐dimensional crystal surface show two connectors per unit cell confirming the p42 1 2 symmetry. The height of the connector was estimated to be at least 7.6 nm, a value close to that found in previous studies using different techniques. The 12 subunits of the wide connector domain were clearly resolved and showed a right‐handed vorticity. The channel running along the connector had a diameter of 3.7 nm in the wide domain, while it was 1.7 nm in the narrow domain end, thus suggesting a tronco‐conical channel shape. Moreover, the narrow connector end appears to be rather flexible. When the force applied to the stylus was between 50 and 100 pN, the connector end was fully extended. At forces of ∼150 pN, these ends were pushed towards the crystal surface. The complementation of the AFM data with the three‐dimensional reconstruction obtained from electron microscopy not only confirmed the model proposed, but also offers new insights that may help to explain the role of the connector in DNA packing.