8iud

From Proteopedia

Crystal Structure of bacterial defense protein GajB

Structural highlights

8iud is a 1 chain structure with sequence from Bacillus cereus VD045. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2Å
Ligands:
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

GAJB_BACC6 Component of antiviral defense system Gabija type I, composed of GajA and GajB. Expression of Gabija type I in B.subtilis (strain BEST7003) confers resistance to phages phi105, phi29, rho14, SpBeta and SBSphiC (PubMed:29371424). Expression of Gabija type I in E.coli B (strain ATCC 11303) confers resistance to phage T7 (PubMed:33885789). May be a helicase or contribute to GajA activation (Probable).^[1] ^[2] ^[3] ^[4]

Publication Abstract from PubMed

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.

Structural and functional investigation of GajB protein in Gabija anti-phage defense.,Oh H, Koo J, An SY, Hong SH, Suh JY, Bae E Nucleic Acids Res. 2023 Nov 27;51(21):11941-11951. doi: 10.1093/nar/gkad951. PMID:37897358^[5]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Doron S, Melamed S, Ofir G, Leavitt A, Lopatina A, Keren M, Amitai G, Sorek R. Systematic discovery of antiphage defense systems in the microbial pangenome. Science. 2018 Mar 2;359(6379):eaar4120. PMID:29371424 doi:10.1126/science.aar4120
↑ Cheng R, Huang F, Wu H, Lu X, Yan Y, Yu B, Wang X, Zhu B. A nucleotide-sensing endonuclease from the Gabija bacterial defense system. Nucleic Acids Res. 2021 May 21;49(9):5216-5229. PMID:33885789 doi:10.1093/nar/gkab277
↑ Doron S, Melamed S, Ofir G, Leavitt A, Lopatina A, Keren M, Amitai G, Sorek R. Systematic discovery of antiphage defense systems in the microbial pangenome. Science. 2018 Mar 2;359(6379):eaar4120. PMID:29371424 doi:10.1126/science.aar4120
↑ Cheng R, Huang F, Wu H, Lu X, Yan Y, Yu B, Wang X, Zhu B. A nucleotide-sensing endonuclease from the Gabija bacterial defense system. Nucleic Acids Res. 2021 May 21;49(9):5216-5229. PMID:33885789 doi:10.1093/nar/gkab277
↑ Oh H, Koo J, An SY, Hong SH, Suh JY, Bae E. Structural and functional investigation of GajB protein in Gabija anti-phage defense. Nucleic Acids Res. 2023 Nov 27;51(21):11941-11951. PMID:37897358 doi:10.1093/nar/gkad951