| Autor: |
Nirwan, Neha, Itoh, Yuzuru, Singh, Pratima, Bandyopadhyay, Sutirtha, Vinothkumar, Kutti R., Amunts, Alexey, Saikrishnan, Kayarat |
| Zdroj: |
Nature Communications; 7/11/2019, Vol. 10 Issue 1, pN.PAG-N.PAG, 1p |
| Abstrakt: |
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. McrBC is a bacterial antiphage defense system that cleaves methylated DNA and is composed of the AAA+ GTPase motor McrB and the endonuclease McrC. Here, the authors present the cryo-EM structure of E. coli McrBC that reveals how McrC inserts a stalk-like structure into the pore of the ring-shaped McrB hexamer and discuss mechanistic implications. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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