Catalytic Domains in RNA-Binding Proteins

Introduction

A subset of the large family of RNA-binding proteins also contain catalytic domains. These multidomain enzymes play important roles in regulating gene expression, nucleic acid metabolism, immunity, and other cellular processes. In most cases, RNA binding is mediated by the presence of one or more double-stranded RNA (dsRNA) binding domains (dsRBDs) (cross reference to: “Double Stranded RNA and End-Recognition Domains”). The dsRBD binds to dsRNAs and to RNAs that contain duplex regions. Although dsRNA binding is primarily determined by shape complementarily, some dsRBDs recognize sequence in the minor groove.

Enzyme Families

A prominent group of enzymes that contain the dsRBD are endonucleases of the RNase III family that function to cleave dsRNAs. The RNase III enzymes generate 5′ phosphoryl and 3′ hydroxyl ends with a two-nucleotide (nt) 3′ overhang within their dsRNA products. These proteins contain one or two endonuclease domains; a dsRBD and, in some cases, additional...