Studies on the RNA of Bacteriophage MS2

Author: Strauss, James Henry

Year: 1967

Degree: Dissertation (Ph.D.)

Advisor: Delbruck, Max

Committee Member: Unknown, Unknown

Option: Biochemistry and Molecular Biophysics

DOI: 10.7907/1WZB-AY91

Abstract

The first part of this dissertation contains a publication which discusses the purification and properties of bacteriophage MS2 and its RNA, including the RNA content of the virus, and light scattering particle weights and sedimentation properties of the virus and its RNA. A short discussion of this publication in light of later results is included.

An infectivity assay for MS2-RNA is characterized in Part II. The results of varying several parameters of the assay are presented, and the effects on the assay of competing RNA's and external ribonuclease are discussed.

Part III presents the initial kinetics of degradation of MS2-RNA by ribonuclease, heat, and alkali, as followed by the exponential decline in RNA infectivity. The turnover number of pancreatic ribonuclease is independent of RNA concentration between 10¹¹ and 10¹⁵ RNA molecules per ml. Inactivation at high pH is almost proportional to the hydroxyl ion concentration between pH 11 and 12.3. The activation energy for thermal inactivation is 22 kcal./mole.

Part IV contains studies on the denaturation of MS2-RNA, of a double-stranded form of RNA, and of rG:rC by thermal means and with organic solvents. Evidence is presented that in dimethylsulfoxide RNA is completely denatured at room temperature.

Part V describes the centrifugal properties of MS2-RNA. The RNA is shown to possess no covalent configurational restraints by the presence of but a single component when sedimented under denaturing conditions, by the correspondence between the decline in infectivity produced by ribonuclease and the production of RNA fragments, and the coincident sedimentation of the RNA infectivity with the bulk RNA under a variety of conditions, including sedimentation through dimethylsulfoxide. The RNA chain does hydrogen-bond to itself, however, giving rise to multiple, homogeneous, infective components under certain conditions.

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