Structural highlights
FunctionABPA_ECOLI Part of an antiviral system composed of AbpA and AbpB; when both are expressed from a plasmid they confer resistance to phages T2, T4, T7 and lambda but not RB32 or RB69. Resistance is temperature dependent, it can be seen at 30 degrees Celsius but not at 37 or 42 degrees Celsius. The system impairs phage but not bacterial DNA synthesis (shown for T4, T7 and lambda). Partially suppressed by mutations in T4 gene 41, a replicative helicase.[1] Publication Abstract from PubMedBacteria have developed a variety of immune systems to combat phage infections. The Hachiman system is a novel prokaryotic antiphage defense system comprising HamA and HamB proteins, which contains the DUF1837 and helicase domains, respectively. However, the defense mechanism remains only partially understood. Here, we present the cryo-electron microscopy (cryo-EM) structure of the Hachiman defense system featuring a fusion of Cap4 nuclease domain within HamA. Further structure analysis indicates that the DUF1837 domain on HamA resembles the PD-(D/E)XK nuclease but lacks active sites. Bioinformatics analysis reveals that catalytically inactive DUF1837 domains often recruit other functional domains to fulfill anti-phage defense. HamA interacts with HamB to form a heterodimer HamAB to mediate ATP hydrolysis and execute DNA cleavage, thus implementing antiphage defense. Our findings elucidate the structural basis of the Hachiman defense complex, highlighting the critical roles of the helicase and nuclease in prokaryotic immunity. Bacterial Hachiman complex executes DNA cleavage for antiphage defense.,Cui Y, Dai Z, Ouyang Y, Fu C, Wang Y, Chen X, Yang K, Zheng S, Wang W, Tao P, Guan Z, Zou T Nat Commun. 2025 Mar 17;16(1):2604. doi: 10.1038/s41467-025-57851-1. PMID:40097437[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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This page was last modified 21:38, 26 March 2025.