Mar 12, 2024 · Structures of complexes containing GajA and GajB proteins of the prokaryotic Gabija anti-phage defence system reveal the mechanism of its activation after DNA cleavage upon ATP depletion.

Gabija protein A (GajA) is a DNA endonuclease that tetramerizes to form the core of the anti-phage defence complex. Two sets of Gabija protein B (GajB) dimers dock at opposite sides of the complex and create a 4:4 GajA–GajB assembly (hereafter, GajAB) that is essential for phage resistance in vivo.

Jan 29, 2024 · The Gabija system is a newly discovered bacterial immune system that consists of GajA and GajB. Here we report the cryo-EM structure of the Gabija complex from Bacillus cereus VD045 at 3.6 Å, which provides the direct evidence of interactions between GajA and GajB. The Gabija complex is an octameric ring structure with four GajA and four GajB.

Oct 28, 2023 · In this study, we report the results of structural and functional analyses of GajB protein from the Gabija anti-phage defense system in B. cereus VD045. The crystal structure of GajB was determined and compared with that of UvrD helicase.

Jul 23, 2023 · GajA was identified as a DNA nicking endonuclease but the functions of GajB and the complex remain unknown. Here, we show that synergy between GajA-mediated DNA cleavage and nucleotide hydrolysis by GajB initiates efficient abortive infection defense against virulent bacteriophages.

Nov 22, 2023 · Gabija protein A (GajA) is a DNA endonuclease that tetramerizes to form the core of the anti-phage defence complex. Two sets of Gabija protein B (GajB) dimers dock at opposite sides of the...

Here, to explore how the Gabija system is activated for anti-phage defence, we report its cryo-electron microscopy structures in five states, including apo GajA, GajA in complex with DNA, GajA bound by ATP, apo GajA-GajB, and GajA-GajB in complex with ATP and Mg 2+.

Jan 29, 2024 · GajA is an OLD nucleases family protein, while GajB belongs to the SF1 helicases. The Gabija complex has sequence-specific DNA nuclease activity and prefers circular rather than linear...

Apr 16, 2024 · Here, using cryo-EM and biochemistry, the authors show that GajA and GajB form a supramolecular complex with a stoichiometry of 4:4 to promote anti-phage defense.

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