diff --git a/content/3.defense-systems/gabija.md b/content/3.defense-systems/gabija.md index 7327868ee424e9e020bbca6b701dc9da3c5f604a..9398eaeb93029c105dc4327832e7a2c4fb2f0a7f 100644 --- a/content/3.defense-systems/gabija.md +++ b/content/3.defense-systems/gabija.md @@ -24,13 +24,13 @@ relevantAbstracts: ## 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 (:ref{doi=10.1126/science.aar4120}). Both proteins are necessary for defense and are forming a heteromeric octamer complex: GajA forms a central tetramer surrounded by two GajB dimers (ref:{doi=10.1101/2023.05.01.538945, 10.1093/nar/gkad951}). A phage protein inhibiting Gabija function was described, Gabidja anti defense 1 (Gad1)(:ref{doi=10.1101/2023.05.01.538945,10.1101/2023.05.01.538930}). +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 :ref{doi=10.1126/science.aar4120}. Both proteins are necessary for defense and are forming a heteromeric octamer complex: GajA forms a central tetramer surrounded by two GajB dimers ref:{doi=10.1101/2023.05.01.538945, 10.1093/nar/gkad951}. A phage protein inhibiting Gabija function was described, Gabidja anti defense 1 (Gad1) :ref{doi=10.1101/2023.05.01.538945, 10.1101/2023.05.01.538930}. ## 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 nucleotides concentrations. It was hypothesized that upon nucleotide depletion during phage infection, GajA would become activated (:ref{doi=10.1093/nar/gkab277}). -Moreover, a later study suggests that the *gajB* gene encode 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 (:ref{doi=10.1016/j.chom.2023.06.014}). +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 nucleotides concentrations. It was hypothesized that upon nucleotide depletion during phage infection, GajA would become activated :ref{doi=10.1093/nar/gkab277}. +Moreover, a later study suggests that the *gajB* gene encode 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 :ref{doi=10.1016/j.chom.2023.06.014}. Therefore, both proteins would be cooperating to achieve both nucleotide depletion and DNA cleavage, causing abortive infection. ## Example of genomic structure