Structure-based mechanism for activation of the AAA+ GTPase McrB by the endonuclease McrC.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31296862.
- Also identified by DOI 10.1038/s41467-019-11084-1 and PMC identifier 6624300.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The AAA+ GTPase McrB powers DNA cleavage by the endonuclease McrC. The GTPase itself is activated by McrC. The architecture of the GTPase and nuclease complex, and the mechanism of their activation remained unknown. Here, we report a 3.6 Å structure of a GTPase-active and DNA-binding deficient construct of McrBC. Two hexameric rings of McrB are bridged by McrC dimer. McrC interacts asymmetrically with McrB protomers and inserts a stalk into the pore of the ring, reminiscent of the γ subunit complexed to α<sub>3</sub>β<sub>3</sub> of F<sub>1</sub>-ATPase. Activation of the GTPase involves conformational changes of residues essential for hydrolysis. Three consecutive nucleotide-binding pockets are occupied by the GTP analogue 5'-guanylyl imidodiphosphate and the next three by GDP, which is suggestive of sequential GTP hydrolysis.
Medical subject headings
- AAA Domain
- DNA Restriction Enzymes
- Escherichia coli
- Escherichia coli Proteins