Dimeric structure of pseudokinase RNase L bound to 2-5A reveals a basis for interferon-induced antiviral activity.
Publication Type:Journal Article
Source:Mol Cell, Volume 53, Issue 2, p.221-34 (2014)
Keywords:Adenine Nucleotides, Adenosine Diphosphate, Adenylyl Imidodiphosphate, Animals, Ankyrin Repeat, Binding Sites, Crystallography, X-Ray, Dimerization, Encephalomyocarditis virus, Endoribonucleases, HeLa Cells, Humans, Models, Molecular, Mutagenesis, Site-Directed, Oligoribonucleotides, Picornaviridae, Protein Structure, Tertiary, Scattering, Radiation, Structure-Activity Relationship, Sus scrofa
<p>RNase L is an ankyrin repeat domain-containing dual endoribonuclease-pseudokinase that is activated by unusual 2,'5'-oligoadenylate (2-5A) second messengers and which impedes viral infections in higher vertebrates. Despite its importance in interferon-regulated antiviral innate immunity, relatively little is known about its precise mechanism of action. Here we present a functional characterization of 2.5 Å and 3.25 Å X-ray crystal and small-angle X-ray scattering structures of RNase L bound to a natural 2-5A activator with and without ADP or the nonhydrolysable ATP mimetic AMP-PNP. These studies reveal how recognition of 2-5A through interactions with the ankyrin repeat domain and the pseudokinase domain, together with nucleotide binding, imposes a rigid intertwined dimer configuration that is essential for RNase catalytic and antiviral functions. The involvement of the pseudokinase domain of RNase L in 2-5A sensing, nucleotide binding, dimerization, and ribonuclease functions highlights the evolutionary adaptability of the eukaryotic protein kinase fold.</p>