PDBsum entry 4dyc

Viral protein

PDB id: 4dyc

Contents

Protein chains

123 a.a.

130 a.a.

Waters ×205

PDB id:

4dyc

Name:

Viral protein

Title:

Crystal structure of the terminase small subunit gp1 with d19r mutation of the bacterial virus sf6

Structure:

Terminase small subunit. Chain: a, b. Engineered: yes

Source:

Salmonella phage hk620. Organism_taxid: 155148. Strain: bacteriophage sf6. Gene: gp1. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

1.80Å R-factor: 0.208 R-free: 0.235

Authors:

H.Zhao,L.Tang

Key ref:

H.Zhao et al. (2012). Structural and functional studies of the phage Sf6 terminase small subunit reveal a DNA-spooling device facilitated by structural plasticity. J Mol Biol, 423, 413-426. PubMed id: 22858866

Date:

28-Feb-12 Release date: 17-Oct-12

Protein chain

Q9AZ01  (Q9AZ01_BPHK6) -  Terminase small subunit from Enterobacteria phage HK620

Seq: 140 a.a.

Struc: 123 a.a.

Protein chain

Q9AZ01  (Q9AZ01_BPHK6) -  Terminase small subunit from Enterobacteria phage HK620

Seq: 140 a.a.

Struc: 130 a.a.

J Mol Biol 423:413-426 (2012)

PubMed id: 22858866

Structural and functional studies of the phage Sf6 terminase small subunit reveal a DNA-spooling device facilitated by structural plasticity.

H.Zhao, Y.N.Kamau, T.E.Christensen, L.Tang.

ABSTRACT

In many DNA viruses, genome packaging is initiated by the small subunit of the packaging terminase, which specifically binds to the packaging signal on viral DNA and directs assembly of the terminase holoenzyme. We have experimentally mapped the DNA-interacting region on Shigella virus Sf6 terminase small subunit gp1, which occupies extended surface areas encircling the gp1 octamer, indicating that DNA wraps around gp1 through extensive contacts. High-resolution structures reveal large-scale motions of the gp1 DNA-binding domain mediated by the curved helix formed by residues 54-81 and an intermolecular salt bridge formed by residues Arg67 and Glu73, indicating remarkable structural plasticity underlying multivalent, pleomorphic gp1:DNA interactions. These results provide spatial restraints for protein:DNA interactions, which enable construction of a three-dimensional pseudo-atomic model for a DNA-packaging initiation complex assembled from the terminase small subunit and the packaging region on viral DNA. Our results suggest that gp1 functions as a DNA-spooling device, which may transform DNA into a specific architecture appropriate for interaction with and cleavage by the terminase large subunit prior to DNA translocation into viral procapsid. This may represent a common mechanism for the initiation step of DNA packaging in tailed double-stranded DNA bacterial viruses.