1 Physical Properties of RNA Bacteriophages and Their RNA

Abstract

INTRODUCTION
All of the known RNA bacteriophages are regular polyhedra with an outside diameter of 250 Å. Their small size, ease of preparation and simplicity have encouraged extensive studies of their structure by both physical and chemical techniques. This has led to a rather detailed understanding of many aspects of their structure, which we will review below, but has thus far left us short of a complete structure. Such questions as how the RNA is folded within the particle, how the coat protein interacts with itself and the RNA, where the maturation or A protein is located, and how it interacts with the coat protein and/or the RNA are all largely unanswered. Obviously, suitable crystallization of the virus would eventually reveal answers to some of these questions, but this has not been achieved.

The physical properties of all the RNA phages are very similar, the only major difference being that the serologically distinct phage Qβ and its RNA are about 15% larger than the others (R17, f2, MS2, fr, M12, μ2). We will point out the particular phage used in various studies, but in general the information is applicable to all. We will discuss the physical properties of the phage particle: size, molecular weight, RNA, H₂O content, stability, and various induced structural changes. Then the molecular weight measurements on the RNA and its shape will be discussed, with special emphasis on secondary structure. Previous reviews have also summarized physical properties of the phage particles and their RNA (Zinder 1965; Hoffmann...