9UXI
type II Lamassu, LmuA tetramer
Summary for 9UXI
| Entry DOI | 10.2210/pdb9uxi/pdb |
| EMDB information | 64584 |
| Descriptor | ABC-three component systems C-terminal domain-containing protein (1 entity in total) |
| Functional Keywords | endonuclease; structural maintenance of chromosomes (smc) proteins; dna binding protein, dna binding protein |
| Biological source | Vibrio cholerae |
| Total number of polymer chains | 4 |
| Total formula weight | 178338.88 |
| Authors | |
| Primary citation | Li, M.,Zhao, X.,Zhao, X.,Li, D.,Xiong, W.,Gao, Z.,Huang, L.,An, L.,Gao, Y.,Li, S.,Feng, Y.,Zhang, K.,Zhang, Y. Structural insights into type-I and type-II Lamassu antiphage systems. Nat.Chem.Biol., 2026 Cited by PubMed Abstract: Bacteria have developed a variety of immune systems to combat phage infections. The Lamassu system is a prokaryotic immune system with a core conserved structural maintenance of chromosomes (SMC) superfamily protein LmuB and diverse effectors named LmuA, whose mechanism remains unclear. Here we present a series of cryo-electron microscopy structures of the type-I Lamassu complex from Bacillus cellulasensis and the type-II Lamassu complex from Vibrio cholerae, both in apo and dsDNA-bound states, revealing an unexpected stoichiometry and topological architecture distinct from canonical SMC complexes. Combined structural and biochemical analyses show how the nuclease effector LmuA is sequestered in an inactive monomeric form within the Lamassu complex and, upon sensing foreign DNA ends, dissociates and assembles into an active tetramer capable of DNA cleavage. Our findings elucidate the mechanism by which Lamassu systems detect viral replication and implement antiphage defense, highlighting the roles of SMC proteins in prokaryotic immunity. PubMed: 41482579DOI: 10.1038/s41589-025-02102-z PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (3.64 Å) |
Structure validation
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