A DNA-gated molecular guard controls bacterial Hailong anti-phage defence.

ABSTRACT: Animal and bacterial cells use nucleotidyltransferase (NTase) enzymes to respond to viral infection and control major forms of immune signalling including cGAS-STING innate immunity and CBASS anti-phage defence^1-4. Here 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. Hailong protein B (HalB) is an NTase that converts deoxy-ATP into single-stranded DNA oligomers. 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. We show that HalB DNA signals bind to and repress activation of a partnering Hailong protein A (HalA) effector complex. A 2.0-Å c

SUBMITTER: Tan JMJ 

PROVIDER: S-EPMC12360457 | biostudies-literature | 2025 Jul

REPOSITORIES: biostudies-literature