Awardees

Emily Agnello  |  Kelch Lab  |  NSF Graduate Research Fellowship

As the most abundant and deadliest entities on earth, bacteriophage play an essential role in many biological environments. While there are well-developed phage model systems that have informed our understanding of phage in the past 60 years, these systems have structural limitations. Here, we use a unique thermophilic siphovirus, P74-26, with extraordinary strength and stability to fill in the knowledge gaps that remain and take a closer look at some of the fascinating abilities of a phage that developed under the evolutionary pressure of a hot spring. Double-stranded DNA (dsDNA) viruses, which include bacteriophage along with herpesviruses, adenoviruses, use a powerful ATPase motor to pump their genome into an immature structure called the procapsid. Genome loading leads to immense internal pressure, resulting in a conformational change from a spherical particle to an expanded, pressurized icosahedron. The extreme stability of P74-26 despite high temperature and pressure makes it a novel tool for elucidating the intricacies of phage assembly and thermodynamics. In this study, we will combine cryo-EM, SEC-multi angle light scattering, and mass spectrometry to examine physical and mechanistic aspects of P74-26. A structure of the uniquely long phage tail tube will provide perspective into the mechanism of DNA ejection and possible evolutionary advantages for such length. Additionally, we have found that the major capsid protein spontaneously assembles, allowing us to create a controlled system for determining the essential components for viral head stability.