Affiliation:
1. Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
2. Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan
Abstract
ABSTRACT
Bacteria have developed various defense mechanisms against phages. Abortive infection (Abi), a bacterial defense mechanism, can be achieved through various means, including toxin-antitoxin systems, cyclic oligonucleotide-based antiphage signaling systems, and retrons. AbpA and AbpB (AbpAB) defend against many lytic phages harboring double-stranded DNA genomes in
Escherichia coli
; however, how AbpAB senses phage infection and inhibits its propagation remains unclear. Here, we demonstrated that AbpAB inhibited the growth of the φX174 lytic phage with single-stranded DNA (ssDNA) as well as the lysogenization and induction of the Sakai prophage 5 lysogenic phage. The AbpAB defense system limits T4 and φX174 phage propagation via Abi. AbpA contains a nuclease domain at its N-terminus, and AbpB has an ATP-dependent RNA helicase domain; both domains are required for phage defense. This system is activated by phage Gp32 binding to ssDNA and inhibits
E. coli
growth. Without phage infection, DNA replication inhibitors or defects in the DNA repair factors RecB and RecC activate this system. Therefore, the
E. coli
AbpAB defense system may sense DNA-protein complexes, including the phage-encoded ssDNA-binding protein or those formed by interrupting host DNA replication or repair.
IMPORTANCE
Although numerous phage defense systems have recently been discovered in bacteria, how these systems defend against phage propagation or sense phage infections remains unclear. The
Escherichia coli
AbpAB defense system targets several lytic and lysogenic phages harboring DNA genomes. A phage-encoded single-stranded DNA-binding protein, Gp32, activates this system similar to other phage defense systems such as Retron-Eco8, Hachiman, ShosTA, Nhi, and Hna. DNA replication inhibitors or defects in DNA repair factors activate the AbpAB system, even without phage infection. This is one of the few examples of activating phage defense systems without phage infection or proteins. The AbpAB defense system may be activated by sensing specific DNA-protein complexes.
Funder
MEXT | Japan Society for the Promotion of Science
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
1 articles.
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