Structure, Reactivity, and Biology of Double-Stranded RNA

This chapter focuses on the structure and physicochemical properties of double stranded RNA (dsRNA); on the enzymes that degrade, modify, or otherwise modulate dsRNA structure and function; and on protein motifs that specifically recognize dsRNA. It discusses the metabolism and regulatory functions of dsRNA in the prokaryotic cell, as are the functions of dsRNA and dsRNA-specific enzymes in eukaryotic cells. It also covers the mammalian cellular and physiological response to dsRNA and the prospects of dsRNA as a therapeutic agent. The RNA double helix is a ubiquitous structural motif in living organisms. Double stranded RNA is created by a number of biosynthetic pathways and is subsequently degraded, denatured, or specifically modified by enzymatic activities. It also serves as a stable repository of genetic information for many viruses. The diverse functional roles of dsRNA have spurred intensive studies on the biochemical processes that involve dsRNA. The first structural information on dsRNA came from X-ray diffraction analyses of synthetic or naturally occurring dsRNA fibers. Analyses of the structures of prokaryotic antisense RNAs and the precise interactions with their targets provide insight into the dynamics of dsRNA formation and the way gene expression is regulated by RNA–RNA interactions.