5TGE

Thermus Phage P74-26 Large Terminase Nuclease Domain

Summary for 5TGE

• Entry DOI: 10.2210/pdb5tge/pdb
• Descriptor: Phage terminase large subunit (2 entities in total)
• Functional Keywords: nuclease, viral protein
• Biological source: Thermus phage P7426
• Total number of polymer chains: 1
• Total formula weight: 27849.11

Authors

Hilbert, B.J.,Hayes, J.A.,Stone, N.P.,Kelch, B.A. (deposition date: 2016-09-27, release date: 2017-01-25, Last modification date: 2024-03-06)

Primary citation

Hilbert, B.J.,Hayes, J.A.,Stone, N.P.,Xu, R.G.,Kelch, B.A.
The large terminase DNA packaging motor grips DNA with its ATPase domain for cleavage by the flexible nuclease domain.
Nucleic Acids Res., 45:3591-3605, 2017

PubMed Abstract: Many viruses use a powerful terminase motor to pump their genome inside an empty procapsid shell during virus maturation. The large terminase (TerL) protein contains both enzymatic activities necessary for packaging in such viruses: the adenosine triphosphatase (ATPase) that powers DNA translocation and an endonuclease that cleaves the concatemeric genome at both initiation and completion of genome packaging. However, how TerL binds DNA during translocation and cleavage remains mysterious. Here we investigate DNA binding and cleavage using TerL from the thermophilic phage P74-26. We report the structure of the P74-26 TerL nuclease domain, which allows us to model DNA binding in the nuclease active site. We screened a large panel of TerL variants for defects in binding and DNA cleavage, revealing that the ATPase domain is the primary site for DNA binding, and is required for nuclease activity. The nuclease domain is dispensable for DNA binding but residues lining the active site guide DNA for cleavage. Kinetic analysis of DNA cleavage suggests flexible tethering of the nuclease domains during DNA cleavage. We propose that interactions with the procapsid during DNA translocation conformationally restrict the nuclease domain, inhibiting cleavage; TerL release from the capsid upon completion of packaging unlocks the nuclease domains to cleave DNA.

PubMed: 28082398
DOI: 10.1093/nar/gkw1356

Experimental method

X-RAY DIFFRACTION (2.6 Å)