ABSTRACT
In Chapter 10, we learned that the activity of individual genes is influenced by the degree of packaging exhibited by the chromatin domain in which those genes are contained and also by the precise positioning of the nucleosomes in the vicinity of the genes. Although our focus was on higher-order structures such as chromatin and nucleosomes, we recognized that, at a more basic level, the accessibility of the genome is controlled by the interactions between histone proteins and the DNA to which they are attached. These interactions are an example of the central role that DNA-binding proteins play in genome expression. Histones are DNA-binding proteins, as are several of the proteins responsible for transcription of individual genes. There are also DNA-binding proteins that are involved in DNA replication, repair, and recombination, as well as a large group of related proteins that bind to RNA rather than DNA. Many DNA-binding proteins recognize specific nucleotide sequences and bind predominantly to these target sites, whereas others, such as histones, lack sequence specificity and attach at various positions in the genome.
