Phi-6 is a bacteriophage, or phage, a non-pathogenic virus that regulates populations of the bacterium Pseudomonas phaseolicola in soil and is analogous to other animal viruses due to its double-stranded RNA genome and membrane. The P5 lysis protein of phi-6 aids in viral entry and lysis of the host cell. Mutations in the P5 protein caused by prior adaptation to thermal stress affect the virus’s stability in different abiotic environments. While research has been conducted on how these mutations affect the overall stability and fitness of the virus in different extreme environments, the thermal and chemical stability of the P5 variants has not been evaluated in vitro to clarify how single amino acid substitutions influence structural resilience under environmental stressors. Our objective is to assess the thermal and chemical stability of P5 and its variants using circular dichroism (CD). We cloned, expressed and purified WT P5 and its variants, then used CD to determine their melting temperatures (Tm) at neutral pH as well as at various other pHs. This approach will help distinguish how single amino acid substitutions can influence the physical properties of the protein, and how the stability of the protein in vitro is linked to the overall adaptability of the virus.
Wyatt et al. (Sun,) studied this question.