Study of two related configurations of the neck of bacteriophage Ø29

AbstractThe 3-D reconstructed images of two related viral structures, obtained by digital image processing from electron micrographs, have been compared to obtain insight into their morphological differences. The viral structures that were studied are the proteins that connect the head to the tail of bacteriophage Ø29. One of these proteins (p10) is assembled as a dodecamer and, once the DNA has been encapsidated into the viral head, this protein interacts with another viral protein (p11) rendering the viral neck. Biochemical analysis by controlled proteolysis revealed a conformational difference in the structure of p10, depending on whether it is assembled in the connector or in the neck complex. Further structural analysis was carried out by digital image processing and computer graphic techniques. The reconstructed density maps were visualized as solid surface representations to reveal gross morphology, and as translucent models to study the inner details of their structure. The use of different density thresholds also allowed us to distinguish interesting morphological features. A channel present in the connector is closed in the final neck. This closing can be correlated with a rearrangement of the subunits of the connector, probably induced by the interaction of protein p11 with p10