The Structure of the Mammalian RNase H2 Complex Provides Insight into RNA.NA Hybrid Processing to Prevent Immune Dysfunction
The mammalian RNase H2 ribonuclease complex has a critical function in nucleic acid metabolism to prevent immune activation with likely roles in processing of RNA primers in Okazaki fragments during DNA replication, in removing ribonucleotides misinserted by DNA polymerases, and in eliminating RNA {center_dot} DNA hybrids during cell death. Mammalian RNase H2 is a heterotrimeric complex of the RNase H2A, RNase H2B, and RNase H2C proteins that are all required for proper function and activity. Mutations in the human RNase H2 genes cause Aicardi-Goutieres syndrome. We have determined the crystal structure of the three-protein mouse RNase H2 enzyme complex to better understand the molecular basis of RNase H2 dysfunction in human autoimmunity. The structure reveals the intimately interwoven architecture of RNase H2B and RNase H2C that interface with RNase H2A in a complex ideally suited for nucleic acid binding and hydrolysis coupled to protein-protein interaction motifs that could allow for efficient participation in multiple cellular functions. We have identified four conserved acidic residues in the active site that are necessary for activity and suggest a two-metal ion mechanism of catalysis for RNase H2. An Okazaki fragment has been modeled into the RNase H2 nucleic acid binding site providing insight into the recognition of RNA {center_dot} DNA junctions by the RNase H2. Further structural and biochemical analyses show that some RNase H2 disease-causing mutations likely result in aberrant protein-protein interactions while the RNase H2A subunit-G37S mutation appears to distort the active site accounting for the demonstrated substrate specificity modification.
- Research Organization:
- Brookhaven National Laboratory (BNL) National Synchrotron Light Source
- Sponsoring Organization:
- DOE - OFFICE OF SCIENCE
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 1019673
- Report Number(s):
- BNL--95519-2011-JA
- Journal Information:
- Journal of Biological Chemistry, Journal Name: Journal of Biological Chemistry Journal Issue: 6 Vol. 285; ISSN JBCHA3; ISSN 0021-9258
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
99 GENERAL AND MISCELLANEOUS
CATALYSIS
CRYSTAL STRUCTURE
DNA
DNA POLYMERASES
DNA REPLICATION
ENZYMES
GENES
HYDROLYSIS
IMMUNITY
METABOLISM
MUTATIONS
NUCLEIC ACIDS
PROCESSING
PROTEINS
RESIDUES
RNA
RNA PROCESSING
RNA-ASE
SPECIFICITY
SUBSTRATES
national synchrotron light source