1 New Approaches to DNA in the Crystal and in Solution

Abstract

I. INTRODUCTION
We review here the progress that has been made concerning the role of DNA in biology during the years 1979–1988. The first part of this chapter will deal with the use of X-ray crystallography to study the three-dimensional structure of DNA in single crystals at near-atomic resolution. This method led to the discovery of left-handed DNA (Pohl and Jovin 1972; Drew et al. 1978, 1980; Wang et al. 1979; Crawford et al. 1980) and also to the realization that the structure of normal, right-handed DNA depends on its nucleotide sequence (Dickerson and Drew 1981; Wang et al. 1982a; Shakked et al. 1983; McCall et al. 1985; Nelson et al. 1987).

The second part of this chapter will describe how the results from X-ray crystallography made it possible to improve on the methods of studying DNA in solution using enzymes, chemicals, topological methods, “statistical sequencing,” and gel electrophoresis. Such solution studies turned out to be essential in learning more about the properties of DNA at a length of 50–200 bp for which it is difficult if not impossible to form single crystals. In brief, it was found that (1) most of the X-ray structures of short pieces of DNA are relevant to long DNA in solution (Lomonossoff et al. 1981; Drew and Travers 1984, 1985a; Johnston and Rich 1985; Burkhoff and Tullius 1987), (2) the ability of DNA to fold into a tightly curved shape about proteins depends on its nucleotide sequence (Drew and Travers 1985b; Satchwell...