The binding of proteins to DNA and the manipulation of DNA by proteins in such processes as recombination, transcription and topoisomerization are crucial aspects of the biological role of DNA in the living cell. This book provides a comprehensive and lucid discussion of the molecular interactions involved, with the emphasis on our current understanding of the structural and mechanistic basis of these phenomena in both bacteria and higher organisms. Among the questions addressed are: how do proteins recognize specific DNA sequences and structures; how do they melt short regions of DNA prior to transcription and DNA replication; how do DNA binding proteins cooperate to regulate transcription; how is DNA packaged in chromatin, and what is the relevance of DNA structure and topology to these processes? The text assumes a knowledge of basic molecular biology and is suitable for research students and final year undergraduates. This book should be of interest to advanced undergraduate and postgraduate students and research workers in biochemistry, molecular biology and genetics.