Agonist and Antagonist Recognition by RIG-I, a Cytoplasmic Innate Immunity Receptor* Academic Article uri icon

abstract

  • Cytoplasmic RNA receptors are important in the detection of and response to viral infections. We analyzed ligand recognition by the retinoic acid-inducible protein I (RIG-I) protein in biochemical assays and in transiently transfected cells and characterized the requirements for both single- and double-stranded RNA agonists for RIG-I activation of signaling. RIG-I mutants such as K270A and T409A/S411A that were defective in signaling with triphosphorylated single-stranded RNAs were perfectly capable of signaling with dsRNAs. Furthermore, phosphorothioated oligodeoxynucleotides were found to antagonize RIG-I signaling. Both agonists and antagonist bind purified RIG-I protein and a truncated RIG-I protein that lacked the signaling domain. The agonists were necessary to activate RIG-I ATPase activity in vitro, whereas antagonist inhibited ATPase activity. Differential scanning fluorometry showed that RIG-I bound to agonists, and antagonists have different denaturation properties, suggesting a difference in protein conformations. Last, single particle reconstruction was used to generate three-dimensional models of the RIG-I dimers in complex with an agonist and an antagonist. The two complexes exhibited dramatically different structures.

altmetric score

  • 10

author list (cited authors)

  • Ranjith-Kumar, C. T., Murali, A., Dong, W., Srisathiyanarayanan, D., Vaughan, R., Ortiz-Alacantara, J., ... Kao, C. C.

citation count

  • 48

complete list of authors

  • Ranjith-Kumar, CT||Murali, Ayaluru||Dong, Wen||Srisathiyanarayanan, Dharmaiah||Vaughan, Robert||Ortiz-Alacantara, Joanna||Bhardwaj, Kanchan||Li, Xiaojun||Li, Pingwei||Kao, Cheng C

publication date

  • January 2009