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Updated: Nov 23, 2025
Structural Studies of Macromolecules in Solution using Small Angle X-Ray Scattering
Published on: November 5, 2018
ADP-ribose and analogues bound to the deMARylating macrodomain from the bat coronavirus HKU4
Robert G Hammond1, Norbert Schormann2, Robert Lyle McPherson3
1Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL 35294.
Abstract:
Macrodomains are proteins that recognize and hydrolyze ADP ribose (ADPR) modifications of intracellular proteins. Macrodomains are implicated in viral genome replication and interference with host cell immune responses. They are important to the infectious cycle of Coronaviridae and Togaviridae viruses. We describe crystal structures of the conserved macrodomain from the bat coronavirus (CoV) HKU4 in complex with ligands. The structures reveal a binding cavity that accommodates ADPR and analogs via local structural changes within the pocket. Using a radioactive assay, we present evidence of mono-ADPR (MAR) hydrolase activity. In silico analysis presents further evidence on recognition of the ADPR modification for hydrolysis. Mutational analysis of residues within the binding pocket resulted in diminished enzymatic activity and binding affinity. We conclude that the common structural features observed in the macrodomain in a bat CoV contribute to a conserved function that can be extended to other known macrodomains.
Insights
Researchers elucidated the structure and function of a bat coronavirus macrodomain, identifying its ADP-ribose (ADPR) hydrolase activity. This finding offers insights into viral replication and host immune evasion strategies.
Area of Science:
- Biochemistry
- Virology
- Structural Biology
Background:
- Macrodomains are protein modules that bind and hydrolyze ADP-ribose (ADPR) modifications.
- These proteins play roles in viral replication and host immune response interference, particularly for Coronaviridae and Togaviridae viruses.
Purpose of the Study:
- To determine the crystal structures of the conserved macrodomain from bat coronavirus (CoV) HKU4 in complex with ligands.
- To investigate the enzymatic activity and binding characteristics of the bat CoV HKU4 macrodomain.
Main Methods:
- X-ray crystallography to obtain complex structures.
- Radioactive assays to measure mono-ADPR (MAR) hydrolase activity.
- In silico analysis and mutational studies of binding pocket residues.
Main Results:
- Crystal structures revealed a binding cavity accommodating ADPR and analogs through local structural changes.
- Evidence of mono-ADPR (MAR) hydrolase activity was demonstrated using radioactive assays.
- Mutational analysis indicated that residues within the binding pocket are crucial for enzymatic activity and binding affinity.
Conclusions:
- The bat CoV HKU4 macrodomain exhibits conserved structural features and mono-ADPR hydrolase activity.
- These findings contribute to understanding the function of macrodomains in viral infectious cycles and host-pathogen interactions.
