8IUD

Crystal Structure of bacterial defense protein GajB

Summary for 8IUD

• Entry DOI: 10.2210/pdb8iud/pdb
• Descriptor: Gabija protein GajB (2 entities in total)
• Functional Keywords: bacterial antiphage defense system, gabija, gajb, unknown function
• Biological source: Bacillus cereus (strain VD045)
• Total number of polymer chains: 1
• Total formula weight: 57757.23

Authors

Oh, H.,Bae, E. (deposition date: 2023-03-24, release date: 2024-01-31, Last modification date: 2024-11-20)

Primary citation

Oh, H.,Koo, J.,An, S.Y.,Hong, S.H.,Suh, J.Y.,Bae, E.
Structural and functional investigation of GajB protein in Gabija anti-phage defense.
Nucleic Acids Res., 51:11941-11951, 2023

PubMed Abstract: Bacteriophages (phages) are viruses that infect bacteria and archaea. To fend off invading phages, the hosts have evolved a variety of anti-phage defense mechanisms. Gabija is one of the most abundant prokaryotic antiviral systems and consists of two proteins, GajA and GajB. GajA has been characterized experimentally as a sequence-specific DNA endonuclease. Although GajB was previously predicted to be a UvrD-like helicase, its function is unclear. Here, we report the results of structural and functional analyses of GajB. The crystal structure of GajB revealed a UvrD-like domain architecture, including two RecA-like core and two accessory subdomains. However, local structural elements that are important for the helicase function of UvrD are not conserved in GajB. In functional assays, GajB did not unwind or bind various types of DNA substrates. We demonstrated that GajB interacts with GajA to form a heterooctameric Gabija complex, but GajB did not exhibit helicase activity when bound to GajA. These results advance our understanding of the molecular mechanism underlying Gabija anti-phage defense and highlight the role of GajB as a component of a multi-subunit antiviral complex in bacteria.

PubMed: 37897358
DOI: 10.1093/nar/gkad951

Experimental method

X-RAY DIFFRACTION (2 Å)