PDBsum entry 2kca

Viral protein

PDB id: 2kca

Contents

Protein chain

109 a.a. *

* Residue conservation analysis

PDB id:

2kca

Name:

Viral protein

Title:

Gp16

Structure:

Bacteriophage spp1 complete nucleotide sequence. Chain: a. Engineered: yes. Mutation: yes

Source:

Bacillus phage spp1. Bacteriophage spp1. Organism_taxid: 10724. Expressed in: escherichia coli. Expression_system_taxid: 562. Expression_system_variant: de3.

NMR struc:

20 models

Authors:

M.Gallopin,B.Gilquin,S.Zinn-Justin

Key ref:

S.Lhuillier et al. (2009). Structure of bacteriophage SPP1 head-to-tail connection reveals mechanism for viral DNA gating. Proc Natl Acad Sci U S A, 106, 8507-8512. PubMed id: 19433794 DOI: 10.1073/pnas.0812407106

Date:

18-Dec-08 Release date: 02-Jun-09

Protein chain

O48446  (HCP16_BPSPP) -  Head completion protein gp16 from Bacillus phage SPP1

Seq: 109 a.a.

Struc: 109 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1073/pnas.0812407106

Proc Natl Acad Sci U S A 106:8507-8512 (2009)

PubMed id: 19433794

Structure of bacteriophage SPP1 head-to-tail connection reveals mechanism for viral DNA gating.

S.Lhuillier, M.Gallopin, B.Gilquin, S.Brasilès, N.Lancelot, G.Letellier, M.Gilles, G.Dethan, E.V.Orlova, J.Couprie, P.Tavares, S.Zinn-Justin.

ABSTRACT

In many bacterial viruses and in certain animal viruses, the double-stranded DNA genome enters and exits the capsid through a portal gatekeeper. We report a pseudoatomic structure of a complete portal system. The bacteriophage SPP1 gatekeeper is composed of dodecamers of the portal protein gp6, the adaptor gp15, and the stopper gp16. The solution structures of gp15 and gp16 were determined by NMR. They were then docked together with the X-ray structure of gp6 into the electron density of the approximately 1-MDa SPP1 portal complex purified from DNA-filled capsids. The resulting structure reveals that gatekeeper assembly is accompanied by a large rearrangement of the gp15 structure and by folding of a flexible loop of gp16 to form an intersubunit parallel beta-sheet that closes the portal channel. This stopper system prevents release of packaged DNA. Disulfide cross-linking between beta-strands of the stopper blocks the key conformational changes that control genome ejection from the virus at the beginning of host infection.

Selected figure(s)

Figure 4.
Pseudoatomic structure of the SPP1 connector. Gp6 (blue), gp15 (magenta), and gp16 (green) structures resulting from separate docking in the EM connector maps were placed together in the whole-connector reconstruction and refined by using UROX (Cc = 55.3). Side (A) and cut open (B and C) views of the connector are shown. The electrostatic potential surfaces (C) were calculated with PBEQ-Solver (38).

Figure 5.
Gp16 intersubunit disulfide bonding of the stopper region and DNA ejection. (A) Structure of the gp16 stopper. Residues mutated to cysteine are identified by colors. (B and C) Effect of stopper amino acid substitutions to cysteine in monomeric gp16 (B; no cross-linking) and in its dodecameric assembled form found in viral particles (C; formation of covalently bound subunit dimers (upper bands) in oxidation conditions that were efficiently reduced with 4 mM DTT). (D) DNA ejection from virions bearing gp16 mutations was assayed by a DNase protection method that reveals the amount of DNA not released from viral particles (19). Ejection was triggered by receptor addition using a ratio of 1,250 YueB780 dimers (19) per virion in the presence and in the absence of 4 mM DTT. All results were reproduced in at least 3 independent experiments.

Figures were selected by an automated process.