Author Description

Bacteriophages, viruses that infect bacteria, have evolved a variety of complex protein structures to carry their genomes between host cells. These proteins form the virion particle which can be considered a mostly self-assembled protein machine that protects the genome and effects genome entry into new cells. Because bacteriophages (phages) are often found in harsh environments including animal digestive tracts, sewage, and sea water, virion particle proteins are typically very stable and resistant to changes in pH, salts, digestive proteases, and other agents that typically denature or degrade proteins. Bacteriophage T4 long tail fibers are specialized proteins that bind to the host cell surface. They are very long (.160 nm) and thin (.3-5 nm) rigid fibrous multiprotein structures. The high length to width ratio of the long tail fibers (LTFs), rigidity, self-assembling properties plus chemical durability suggest that LTFs could be adapted into a self-patterning nanoscale protein structure or system. Although crystallizing whole tail fibers remains a challenge, structural data on fiber fragments, related trimeric protein fibers, and other data suggest that some type of repetitive beta secondary structure comprises part of the rigid rod portions of the tail fibers. The presence of segments of beta structure arising from mostly local interactions also support the proposition that tail fibers can withstand a variety of modifications without compromising the overall structure and function of the bacteriophage. Toward the goal of creating structured assemblies we have constructed and tested a variety of tail fibers with alterations in gp 37, which forms the distal end of the native tail fiber, as well as developed an improved purification method for the assembled tail fiber. The alterations include deletions to reduce the overall length and modifications to a key segment where assembly is initiated to improve assembly in vitro. We have also added a variety of attachment