Studies on the Biosynthesis of Studies of ØX174 Coat Protein

Citation

Krane, Stanley Garson (1966) Studies on the Biosynthesis of Studies of ØX174 Coat Protein. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/1MXF-6632. https://resolver.caltech.edu/CaltechETD:etd-09272002-131251

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. A serum blocking power (SBP) assay for [phi]X174 coat protein, which depends on the ability of whole phage or certain phage components to combine with antiphage serum, was developed. This assay registers complete [phi]X, both viable and nonviable, and 70S particles, but not chemically prepared 5S subunits. Studies on the growth of wild type [phi]X, at 37[degrees], showed that SBP synthesis begins at about 5 min, under conditions such that the eclipse ends at 6 to 8 min. Although the curves for SBP and intracellular phage growth have the same shape, the titer of SBP phage equivalents exceeds that of infectious progeny particles at all times. The excess SBP is found in the form of 70S particles, complete but noninfectious phage, and subunits that sediment at about 15S. Chloramphenicol, 5-fluorouracil deoxyriboside, and phleomycin when present at the time of infection each produce essentially complete inhibition of SBP synthesis. These results suggest that at least one complete RF molecule (the double stranded form of [phi]X DNA) must be made in order for SBP synthesis to occur. Several temperature sensitive [...] mutants were studied for their ability to produce SBP at 40[degrees]C (nonpermissive conditions for production of infectious phage). Most of the twenty-six mutants examined did make SBP at 40[degrees]C; however, mutant [...] 79 definitely did not. Studies were made on the physical state of the SBP synthesized, at 40[degrees]C, by the mutants [...] Y, 9, and [...] 4 by the technique of sucrose gradient velocity centrifugation. The results showed that [...] Y, and [...] 9 make their SBP principally in the form of subunits that sediment at approximately 15S. The mutant [...] 4 makes its SBP principally in the form of particles that sediment at 71S. The [...] 4 71S particles may contain both DNA and protein.

Thesis Files