Guegler CK, Teodoro GIC, Srikant S, Chetlapalli K, Doering CR, Ghose DA, Laub MT. A phage-encoded RNA-binding protein inhibits the antiviral activity of a toxin-antitoxin system.
Nucleic Acids Res 2024;
52:1298-1312. [PMID:
38117986 PMCID:
PMC10853763 DOI:
10.1093/nar/gkad1207]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 12/02/2023] [Accepted: 12/06/2023] [Indexed: 12/22/2023] Open
Abstract
Bacteria harbor diverse mechanisms to defend themselves against their viral predators, bacteriophages. In response, phages can evolve counter-defense systems, most of which are poorly understood. In T4-like phages, the gene tifA prevents bacterial defense by the type III toxin-antitoxin (TA) system toxIN, but the mechanism by which TifA inhibits ToxIN remains unclear. Here, we show that TifA directly binds both the endoribonuclease ToxN and RNA, leading to the formation of a high molecular weight ribonucleoprotein complex in which ToxN is inhibited. The RNA binding activity of TifA is necessary for its interaction with and inhibition of ToxN. Thus, we propose that TifA inhibits ToxN during phage infection by trapping ToxN on cellular RNA, particularly the abundant 16S rRNA, thereby preventing cleavage of phage transcripts. Taken together, our results reveal a novel mechanism underlying inhibition of a phage-defensive RNase toxin by a small, phage-encoded protein.
Collapse