Publication Date:
2011-09-29
Description:
Retinoic-acid-inducible gene-I (RIG-I; also known as DDX58) is a cytoplasmic pathogen recognition receptor that recognizes pathogen-associated molecular pattern (PAMP) motifs to differentiate between viral and cellular RNAs. RIG-I is activated by blunt-ended double-stranded (ds)RNA with or without a 5'-triphosphate (ppp), by single-stranded RNA marked by a 5'-ppp and by polyuridine sequences. Upon binding to such PAMP motifs, RIG-I initiates a signalling cascade that induces innate immune defences and inflammatory cytokines to establish an antiviral state. The RIG-I pathway is highly regulated and aberrant signalling leads to apoptosis, altered cell differentiation, inflammation, autoimmune diseases and cancer. The helicase and repressor domains (RD) of RIG-I recognize dsRNA and 5'-ppp RNA to activate the two amino-terminal caspase recruitment domains (CARDs) for signalling. Here, to understand the synergy between the helicase and the RD for RNA binding, and the contribution of ATP hydrolysis to RIG-I activation, we determined the structure of human RIG-I helicase-RD in complex with dsRNA and an ATP analogue. The helicase-RD organizes into a ring around dsRNA, capping one end, while contacting both strands using previously uncharacterized motifs to recognize dsRNA. Small-angle X-ray scattering, limited proteolysis and differential scanning fluorimetry indicate that RIG-I is in an extended and flexible conformation that compacts upon binding RNA. These results provide a detailed view of the role of helicase in dsRNA recognition, the synergy between the RD and the helicase for RNA binding and the organization of full-length RIG-I bound to dsRNA, and provide evidence of a conformational change upon RNA binding. The RIG-I helicase-RD structure is consistent with dsRNA translocation without unwinding and cooperative binding to RNA. The structure yields unprecedented insight into innate immunity and has a broader impact on other areas of biology, including RNA interference and DNA repair, which utilize homologous helicase domains within DICER and FANCM.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3430514/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3430514/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jiang, Fuguo -- Ramanathan, Anand -- Miller, Matthew T -- Tang, Guo-Qing -- Gale, Michael Jr -- Patel, Smita S -- Marcotrigiano, Joseph -- AI080659/AI/NIAID NIH HHS/ -- GM55310/GM/NIGMS NIH HHS/ -- P30 EB009998/EB/NIBIB NIH HHS/ -- R01 AI060389/AI/NIAID NIH HHS/ -- R01 AI060389-11/AI/NIAID NIH HHS/ -- R01 AI080659/AI/NIAID NIH HHS/ -- England -- Nature. 2011 Sep 25;479(7373):423-7. doi: 10.1038/nature10537.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Advanced Biotechnology and Medicine, Department of Chemistry and Chemical Biology, Rutgers University, 679 Hoes Lane West, Piscataway, New Jersey 08854, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21947008" target="_blank"〉PubMed〈/a〉
Keywords:
Adenosine Triphosphatases/metabolism
;
Adenosine Triphosphate/analogs & derivatives/chemistry/metabolism
;
DEAD-box RNA Helicases/*chemistry/immunology/*metabolism
;
Enzyme Activation
;
Fluorometry
;
Humans
;
Immunity, Innate/*immunology
;
Models, Molecular
;
Nucleic Acid Conformation
;
Pliability
;
Protein Binding
;
Protein Structure, Tertiary
;
Proteolysis
;
RNA, Double-Stranded/chemistry/*metabolism
;
RNA-Binding Proteins/chemistry/immunology/metabolism
;
Scattering, Small Angle
;
Structure-Activity Relationship
;
Substrate Specificity
;
Trypsin/metabolism
;
X-Ray Diffraction
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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