Journal of Biological Chemistry
Volume 286, Issue 12, 25 March 2011, Pages 10530-10539
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Protein Structure and Folding
The Structure of the Human RNase H2 Complex Defines Key Interaction Interfaces Relevant to Enzyme Function and Human Disease*

https://doi.org/10.1074/jbc.M110.177394Get rights and content
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Ribonuclease H2 (RNase H2) is the major nuclear enzyme involved in the degradation of RNA/DNA hybrids and removal of ribonucleotides misincorporated in genomic DNA. Mutations in each of the three RNase H2 subunits have been implicated in a human auto-inflammatory disorder, Aicardi-Goutières Syndrome (AGS). To understand how mutations impact on RNase H2 function we determined the crystal structure of the human heterotrimer. In doing so, we correct several key regions of the previously reported murine RNase H2 atomic model and provide biochemical validation for our structural model. Our results provide new insights into how the subunits are arranged to form an enzymatically active complex. In particular, we establish that the RNASEH2A C terminus is a eukaryotic adaptation for binding the two accessory subunits, with residues within it required for enzymatic activity. This C-terminal extension interacts with the RNASEH2C C terminus and both are necessary to form a stable, enzymatically active heterotrimer. Disease mutations cluster at this interface between all three subunits, destabilizing the complex and/or impairing enzyme activity. Altogether, we locate 25 out of 29 residues mutated in AGS patients, establishing a firm basis for future investigations into disease pathogenesis and function of the RNase H2 enzyme.

Crystal Structure
DNA Repair
DNA Replication
RNA-binding Protein
X-ray Crystallography
Aicardi-Goutières Syndrome
RNase H2

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The atomic coordinates and structure factors (codes3P5J and 3P56) have been deposited in the Protein Data Bank, Research Collaboratory for Structural Bioinformatics, Rutgers University, New Brunswick, NJ (http://www.rcsb.org/).

*

This research was funded in part by a Medical Research Council Senior Clinical Fellowship grant (to A. P. J.) and Cancer Research UK grant (to E. Y. J.). The work was also supported by the Wellcome Trust Core Award (Grant 075491/Z04).

The on-line version of this article (available at http://www.jbc.org) contains supplemental Tables S1–S3.

1

Both authors contributed equally to this work.

3

An 1851 Research Fellow.