6V1I
Cryo-EM reconstruction of the thermophilic bacteriophage P74-26 small terminase- symmetric
Summary for 6V1I
Entry DOI | 10.2210/pdb6v1i/pdb |
EMDB information | 21012 |
Descriptor | Small terminase protein (1 entity in total) |
Functional Keywords | small terminase, bacteriophage, helix-turn-helix, motor, viral protein |
Biological source | Thermus virus P74-26 |
Total number of polymer chains | 9 |
Total formula weight | 171727.98 |
Authors | Hayes, J.A.,Hilbert, B.J.,Gaubitz, C.,Stone, N.P.,Kelch, B.A. (deposition date: 2019-11-20, release date: 2020-02-12, Last modification date: 2024-03-06) |
Primary citation | Hayes, J.A.,Hilbert, B.J.,Gaubitz, C.,Stone, N.P.,Kelch, B.A. A thermophilic phage uses a small terminase protein with a fixed helix-turn-helix geometry. J.Biol.Chem., 295:3783-3793, 2020 Cited by PubMed Abstract: Tailed bacteriophages use a DNA-packaging motor to encapsulate their genome during viral particle assembly. The small terminase (TerS) component of this DNA-packaging machinery acts as a molecular matchmaker that recognizes both the viral genome and the main motor component, the large terminase (TerL). However, how TerS binds DNA and the TerL protein remains unclear. Here we identified gp83 of the thermophilic bacteriophage P74-26 as the TerS protein. We found that TerS oligomerizes into a nonamer that binds DNA, stimulates TerL ATPase activity, and inhibits TerL nuclease activity. A cryo-EM structure of TerS revealed that it forms a ring with a wide central pore and radially arrayed helix-turn-helix domains. The structure further showed that these helix-turn-helix domains, which are thought to bind DNA by wrapping the double helix around the ring, are rigidly held in an orientation distinct from that seen in other TerS proteins. This rigid arrangement of the putative DNA-binding domain imposed strong constraints on how TerS can bind DNA. Finally, the TerS structure lacked the conserved C-terminal β-barrel domain used by other TerS proteins for binding TerL. This suggests that a well-ordered C-terminal β-barrel domain is not required for TerS to carry out its matchmaking function. Our work highlights a thermophilic system for studying the role of small terminase proteins in viral maturation and presents the structure of TerS, revealing key differences between this thermophilic phage and its mesophilic counterparts. PubMed: 32014998DOI: 10.1074/jbc.RA119.012224 PDB entries with the same primary citation |
Experimental method | ELECTRON MICROSCOPY (3.8 Å) |
Structure validation
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