Date of Degree


Document Type


Degree Name





John J. Dennehy

Subject Categories

Microbiology | Molecular Biology | Virology


cystoviridae, packaging, Phi6, reoviridae, rotavirus, segmentation


The present study of bacteriophage Phi6 has been preceded by a great number of exploratory studies of its structure and function, and these studies have formed a basis for Phi6's development into a model organism. In this study, two aspects of the model organism have been examined. 1. There are several uncharacterized and presumed untranslated regions (UTRs) in Phi6's 13.3 kilobase-pair dsRNA genome. I examined the impact of specific modification to the 3' UTR of the small segment of bacteriophage Phi6. I determined that modification to the purported UTR of the small segment resulted in severe fitness costs, supporting a functional role for unidentified gene products, secondary RNA structure, or both. 2. Bacteriophage Phi6 packages its dsRNA genomic segments selectively and sequentially through the function of the packaging motor P4 which occupies fivefold vertices of the Phi6 procapsid, and studies support the functioning of one and only one P4 during packaging. The mechanism of this specific phenomenon is not known. I used computational reconstruction of cryoelectron microscopy and examined the occupancy of P4 on the Phi6 procapsid, and acquired insight into the mechanism of assembly and packaging.