Figure 6-6: Schematic of the compression ratchet model of the packaging mechanism. A packaging stroke begins (a) with the alignment of the wide end of the connector with the prohead (gray circle) and the connector channel with the DNA helix (gray triangle); the connector is in a compressed form (right). As the connector narrow end releases the DNA (the wide end holds the DNA) and extends (b), it rotates by 12° counterclockwise with respect to the head such that contact with the DNA shifts to the next pair of connector monomers (left) and two base pairs down the DNA helix (right). During the subsequent compression of the connector (c), the DNA, axially restrained at the narrow end (but released at the wide end), is driven two base pairs into the head (right); concurrently, the wide end of the connector rotates passively 12° counterclockwise with respect to the head (left), reestablishing contact with the head two connector monomers to the left. Reproduced from Grimes et al., 2002, with permission. (for better image quality, click here for tif image, which may be quite large; may also require screen refreshing plus special software to view; or view larger tif in separate window)

Figure 6-1, Figure 6-2, Figure 6-3, Figure 6-4, Figure 6-5, Figure 6-6, Figure 6-7

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