Gabija
Description
Gabija is named after the Lithuanian spirit of fire, protector of home and family. It is a two-gene defense system found in 8.5% of the 4360 bacterial and archeal genomes that were initially analyzed in (N/A) . Both proteins are necessary for defense and are forming a heteromeric octamer complex: GajA forms a central tetramer surrounded by two GajB dimers (N/A, N/A) . A phage protein inhibiting Gabija function was described, Gabidja anti-defense 1 (Gad1) (N/A, N/A) .
Molecular mechanism
The precise mechanism of the Gabija system remains to be fully described, yet studies suggest that it could act through a dual phage inhibition mechanism. GajA was shown to be a sequence-specific DNA-nicking endonuclease, whose activity is inhibited by nucleotide concentration. This nucleotide sensing is mediated by GajA ATPase-like domain. Accordingly, GajA would be fully inhibited at cellular nucleotide concentrations. It was hypothesized that upon nucleotide depletion during phage infection, GajA would become activated (N/A) . Moreover, a later study suggests that the gajB gene encodes an NTPase, which would form a complex with GajA to achieve anti-phage defense. GajB is activated by DNA termini produced by GajA activity and then hydrolyzes (d)A/(d)GTP, depleting essential nucleotides and increasing GajA activity (N/A) . Therefore, both proteins would cooperate to achieve both nucleotide depletion and DNA cleavage, causing abortive infection.
Example of genomic structure
The Gabija is composed of 2 proteins: GajA and GajB.
Here is an example found in the RefSeq database:
The Gabija system in Roseomonas fluvialis (GCF_022846615.1, NZ_AP025637) is composed of 2 proteins GajA (WP_244458879.1) GajB_2 (WP_244458880.1)
Distribution of the system among prokaryotes
Structure
Group | Structure | System | Gene name | Subtype | Proteins in structure | System genes | Prediction type | N genes in sys | pLDDT | iptm+ptm | pDockQ |
|---|---|---|---|---|---|---|---|---|---|---|---|
| No data available | |||||||||||