The Regulatory Domain of the Rig-I Family ATPase Lgp2 Senses Double-Stranded RNA.Pippig, D.A., Hellmuth, J.C., Cui, S., Kirchhofer, A., Lammens, K., Lammens, A., Schmidt, A., Rothenfusser, S., Hopfner, K.P.
(2009) Nucleic Acids Res 37: 2014
- PubMed: 19208642
- DOI: https://doi.org/10.1093/nar/gkp059
- Primary Citation of Related Structures:
- PubMed Abstract:
RIG-I and MDA5 sense cytoplasmic viral RNA and set-off a signal transduction cascade, leading to antiviral innate immune response. The third RIG-I-like receptor, LGP2, differentially regulates RIG-I- and MDA5-dependent RNA sensing in an unknown manner. All three receptors possess a C-terminal regulatory domain (RD), which in the case of RIG-I senses the viral pattern 5'-triphosphate RNA and activates ATP-dependent signaling by RIG-I. Here we report the 2.6 A crystal structure of LGP2 RD along with in vitro and in vivo functional analyses and a homology model of MDA5 RD. Although LGP2 RD is structurally related to RIG-I RD, we find it rather binds double-stranded RNA (dsRNA) and this binding is independent of 5'-triphosphates. We identify conserved and receptor-specific parts of the RNA binding site. Latter are required for specific dsRNA binding by LGP2 RD and could confer pattern selectivity between RIG-I-like receptors. Our data furthermore suggest that LGP2 RD modulates RIG-I-dependent signaling via competition for dsRNA, another pattern sensed by RIG-I, while a fully functional LGP2 is required to augment MDA5-dependent signaling.
Department of Chemistry and Biochemistry, Gene Center, Ludwig-Maximilians University Munich, Munich, Germany.