Structure and activity of a bacterial defense-associated 3'-5' exonuclease.

ABSTRACT: The widespread CBASS (cyclic oligonucleotide-based anti-phage signaling system) immune systems in bacteria protect their hosts from bacteriophage infection by triggering programmed cell death. CBASS systems all encode a cyclic oligonucleotide synthase related to eukaryotic cGAS but use diverse regulators and effector proteins including nucleases, phospholipases, and membrane-disrupting proteins to effect cell death. Cap18 is a predicted 3'-5' exonuclease associated with hundreds of CBASS systems, whose structure, biochemical activities, and biological roles remain unknown. Here we show that Cap18 is a DEDDh-family exonuclease related to the bacterial exonucleases RNase T and Orn and has nonspecific 3'-5' DNA exonuclease activity. Cap18 is commonly found in CBASS systems with associated Cap

SUBMITTER: Liang Q 

PROVIDER: S-EPMC9214754 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature