4DKW

Structure of P22 Large terminase nuclease domain

Summary for 4DKW

• Entry DOI: 10.2210/pdb4dkw/pdb
• Descriptor: Large terminase protein, MAGNESIUM ION, SULFATE ION, ... (4 entities in total)
• Functional Keywords: dna-packaging, large terminase, small terminase, nuclease fold, endonuclease, dna, dna-packaging motor, hydrolase
• Biological source: Enterobacteria phage P22
• Total number of polymer chains: 4
• Total formula weight: 99034.35

Authors

Roy, A.,Cingolani, G. (deposition date: 2012-02-04, release date: 2012-06-27, Last modification date: 2023-09-13)

Primary citation

Roy, A.,Cingolani, G.
Structure of p22 headful packaging nuclease.
J.Biol.Chem., 287:28196-28205, 2012

PubMed Abstract: Packaging of viral genomes into preformed procapsids requires the controlled and synchronized activity of an ATPase and a genome-processing nuclease, both located in the large terminase (L-terminase) subunit. In this paper, we have characterized the structure and regulation of bacteriophage P22 L-terminase (gp2). Limited proteolysis reveals a bipartite organization consisting of an N-terminal ATPase core flexibly connected to a C-terminal nuclease domain. The 2.02 Å crystal structure of P22 headful nuclease obtained by in-drop proteolysis of full-length L-terminase (FL-L-terminase) reveals a central seven-stranded β-sheet core that harbors two magnesium ions. Modeling studies with DNA suggest that the two ions are poised for two-metal ion-dependent catalysis, but the nuclease DNA binding surface is sterically hindered by a loop-helix (L(1)-α(2)) motif, which is incompatible with catalysis. Accordingly, the isolated nuclease is completely inactive in vitro, whereas it exhibits endonucleolytic activity in the context of FL-L-terminase. Deleting the autoinhibitory L(1)-α(2) motif (or just the loop L(1)) restores nuclease activity to a level comparable with FL-L-terminase. Together, these results suggest that the activity of P22 headful nuclease is regulated by intramolecular cross-talk with the N-terminal ATPase domain. This cross-talk allows for precise and controlled cleavage of DNA that is essential for genome packaging.

PubMed: 22715098
DOI: 10.1074/jbc.M112.349894

Experimental method

X-RAY DIFFRACTION (2.02 Å)