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bioRxiv · 10.1101/2023.08.07.552356

Molecular basis of Gabija anti-phage supramolecular assemblies

Yang, X.·Shen, Z.·Lin, Q.·Fu, T.
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Abstract

As one of the most prevalent anti-phage defense systems in prokaryotes, Gabija consists of a Gabija protein A (GajA) and a Gabija protein B (GajB). The assembly and function of the Gabija system remain unclear. Here we present cryo-EM structures of GajA and the GajAB complex, revealing tetrameric and octameric assemblies, respectively. In the center of the complex, GajA assembles into a symmetric tetramer, which recruits two sets of GajB dimer at opposite sides of the complex, resulting in a 4:4 GajAB supramolecular complex for anti-phage defense. Further biochemical analysis showed that GajA alone is sufficient to cut double-stranded DNA and plasmid DNA, which can be inhibited by ATP. Unexpectedly, the GajAB displays enhanced activity for plasmid DNA, suggesting a role of substrate selection by GajB. Together, our study defines a framework for understanding anti-phage immune defense by the GajAB complex.

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Yang, X., Shen, Z., Lin, Q., Fu, T.. 2023-08-07. Molecular basis of Gabija anti-phage supramolecular assemblies. https://doi.org/10.1101/2023.08.07.552356

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