Conte Amy N, Ruchel Madison E, Ridgeway Samantha M, Kibby Emily M, Nagy Toni A, Whiteley Aaron T
Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA.
Department of Biology, Front Range Community College, Longmont, CO, USA.
bioRxiv. 2024 Dec 19:2024.06.04.597415. doi: 10.1101/2024.06.04.597415.
Bacteria encode a wide range of antiphage systems and a subset of these proteins are homologous to components of the human innate immune system. Mammalian nucleotide-binding and leucine-rich repeat containing proteins (NLRs) and bacterial NLR-related proteins use a central NACHT domain to link detection of infection with initiation of an antimicrobial response. Bacterial NACHT proteins provide defense against both DNA and RNA phages. Here we determine the mechanism of RNA phage detection by the bacterial NLR-related protein bNACHT25 in . bNACHT25 was specifically activated by ssRNA phages and analysis of MS2 phage escaper mutants that evaded detection revealed a critical role for Coat Protein (CP). A genetic assay confirmed CP was sufficient to activate bNACHT25 but the two proteins did not directly interact. Instead, we found bNACHT25 requires the host chaperone DnaJ to detect CP. Our data suggest that bNACHT25 detects a wide range of phages by guarding a host cell process rather than binding a specific phage-derived molecule.
细菌编码多种抗噬菌体系统，其中一部分蛋白质与人类先天免疫系统的组成部分同源。哺乳动物含核苷酸结合和富含亮氨酸重复序列的蛋白质（NLRs）以及细菌NLR相关蛋白利用中央NACHT结构域将感染检测与抗菌反应的启动联系起来。细菌NACHT蛋白对DNA和RNA噬菌体均提供防御作用。在此，我们确定了细菌NLR相关蛋白bNACHT25在……中检测RNA噬菌体的机制。bNACHT25被单链RNA噬菌体特异性激活，对逃避检测的MS2噬菌体逃逸突变体的分析揭示了外壳蛋白（CP）的关键作用。一项遗传学检测证实CP足以激活bNACHT25，但这两种蛋白质并不直接相互作用。相反，我们发现bNACHT25需要宿主伴侣蛋白DnaJ来检测CP。我们的数据表明，bNACHT25通过守护宿主细胞过程而非结合特定的噬菌体衍生分子来检测多种噬菌体。
