Evasion of antiviral bacterial immunity by phage tRNAs
Aa Haeruman Azam, Kohei Kondo, Kotaro Chihara, Tomohiro Nakamura, Shinjiro Ojima, Wenhan Nie, Azumi Tamura, Wakana Yamashita, Yo Sugawara, Motoyuki Sugai, Longzhu Cui, Yoshimasa Takahashi, Koichi Watashi, Kotaro Kiga
Abstract
Abstract Retrons are bacterial genetic elements that encode a reverse transcriptase and, in combination with toxic effector proteins, can serve as antiphage defense systems. However, the mechanisms of action of most retron effectors, and how phages evade retrons, are not well understood. Here, we show that some phages can evade retrons and other defense systems by producing specific tRNAs. We find that expression of retron-Eco7 effector proteins (PtuA and PtuB) leads to degradation of tRNA Tyr and abortive infection. The genomes of T5 phages that evade retron-Eco7 include a tRNA-rich region, including a highly expressed tRNA Tyr gene, which confers protection against retron-Eco7. Furthermore, we show that other phages (T1, T7) can use a similar strategy, expressing a tRNA Lys , to counteract a tRNA anticodon defense system (PrrC170).