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Structure-based mechanism for activation of the AAA+ GTPase McrB by the endonuclease McrC.

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 α₃β₃ of F₁-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.

SUBMITTER: Nirwan N

PROVIDER: S-EPMC6624300 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Structure-based mechanism for activation of the AAA+ GTPase McrB by the endonuclease McrC.

Nirwan Neha N Itoh Yuzuru Y Singh Pratima P Bandyopadhyay Sutirtha S Vinothkumar Kutti R KR Amunts Alexey A Saikrishnan Kayarat K

Nature communications 20190711 1

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 comp ...[more]

PMID: 31296862

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