RADAR
Description
RADAR (Restriction by an Adenosine Deaminase Acting on RNA) is comprised of two genes, encoding respectively for an adenosine triphosphatase (RdrA) and a divergent adenosine deaminase (RdrB), which are in some cases associated with a small membrane protein (RdrC or D). They were first uncovered in a study exploring the content of defense islands (N/A) .
Molecular mechanism
In the initial study describing RADAR, RADAR was found to perform RNA editing of adenosine to inosine during phage infection (N/A) . Editing sites were broadly distributed on the host transcriptome, which could prove deleterious leading to observed growth arrest of RADAR upon phage infection. Further structural studies revealed potentially different mechanisms of actions (N/A, N/A) . RdrA and RdrB assemble to form a giant 10 MDa complex. The RADAR defense system limits phage replication by catalyzing ATP deamination. Within this system, RdrB functions as an adenosine deaminase, leading to the buildup of ITP (Inosine Tri-Phosphate) and dITP. RdrA induces RdrB activity and potentially regulates the detection of phage infections.
Example of genomic structure
A total of 2 subsystems have been described for the RADAR system.
Here is some examples found in the RefSeq database:
The radar_I system in Vibrio splendidus (GCF_022812155.1, NZ_CP089205) is composed of 2 proteins rdrA_I (WP_243585344.1) rdrB_I (WP_243585345.1)
The radar_II system in Enterobacter sp. JH25 (GCF_021725435.1, NZ_CP091319) is composed of 3 proteins rdrD_II (WP_022649082.1) rdrB_II (WP_227746616.1) rdrA_II (WP_022649084.1)
Distribution of the system among prokaryotes
Structure
Experimentally determined structure
From (N/A) in Escherichia coli:
From (N/A) in Streptococcus suis:
From (N/A) in Escherichia coli: