Concepedia

Abstract

One of the major unanswered questions in molecular biology today concerns the ability of a class of proteins known as DNA-binding proteins to recognize specific base sequences in DNA and to bind tightly to these sites. Such noncovalent associations play a key role in regulating gene expression—a process that involves information transfer, first from DNA to RNA and then from RNA to proteins (see Watson 1976; Stryer 1980). The first step in this readout process involves tight binding of a protein known as the RNA polymerase enzyme to specific DNA sites called promoters. The details of this interaction are complex and largely unknown; however, it is generally agreed that at some stage local disruption of hydrogen bonds connecting base pairs occurs to allow the stepwise polymerization of monomelic precursors into RNA. This melting process is assisted by the sigma factor, a protein that binds tightly to the core polymerase enzyme...