The unedited manuscript unveils a new family of bacterial defense systems called Hailong, utilizing NTase enzymes to respond to viral infections and enhance immune signaling. HalB is a key NTase that synthesizes DNA signals from deoxy-ATP, with detailed X-ray crystal structures illustrating its enzymatic process. These signals interact with the HalA effector complex, repressing its activation. The study employs cryo-EM to elucidate the structural dynamics of the HalA-DNA complex, highlighting a crown domain that plays a pivotal role in regulating immune responses against phage attacks.
We discover a family of bacterial defence systems, which we name Hailong, that use NTase enzymes to constitutively synthesize DNA signals and guard against phage infection.
A series of X-ray crystal structures define a stepwise mechanism of HalB DNA synthesis initiated by a C-terminal tyrosine residue that enables de novo enzymatic priming.
Our results explain how inhibitory nucleotide immune signals cause viral DNA exonucleases required for phage replication to trigger protective changes in host cells.
A 2.0 A cryo-EM structure of the HalA-DNA complex reveals a unique crown domain that binds the DNA signal and controls activation of the immune response.
#bacterial-defense-systems #nucleotidyltransferase #phage-biology #x-ray-crystallography #cgas-sting-immune-response
Collection
[
|
...
]