7CN7 image
Deposition Date 2020-07-30
Release Date 2020-10-14
Last Version Date 2024-11-13
Entry Detail
PDB ID:
7CN7
Keywords:
Title:
T4 phage spackle protein gp61.3 complex with lysozyme domain of gp5 tail lysozyme
Biological Source:
Source Organism:
Method Details:
Experimental Method:
Resolution:
1.15 Å
R-Value Free:
0.12
R-Value Work:
0.10
R-Value Observed:
0.10
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:Baseplate central spike complex protein gp5
Gene (Uniprot):5
Chain IDs:A
Chain Length:181
Number of Molecules:1
Biological Source:Enterobacteria phage T4
Polymer Type:polypeptide(L)
Molecule:Protein spackle
Gene (Uniprot):sp
Chain IDs:B (auth: C)
Chain Length:75
Number of Molecules:1
Biological Source:Enterobacteria phage T4
Primary Citation
Structure and Function of the T4 Spackle Protein Gp61.3.
Viruses 12 ? ? (2020)
PMID: 32987925 DOI: 10.3390/v12101070

Abstact

The bacteriophage T4 genome contains two genes that code for proteins with lysozyme activity-e and 5. Gene e encodes the well-known T4 lysozyme (commonly called T4L) that functions to break the peptidoglycan layer late in the infection cycle, which is required for liberating newly assembled phage progeny. Gene product 5 (gp5) is the tail-associated lysozyme, a component of the phage particle. It forms a spike at the tip of the tail tube and functions to pierce the outer membrane of the Escherichia coli host cell after the phage has attached to the cell surface. Gp5 contains a T4L-like lysozyme domain that locally digests the peptidoglycan layer upon infection. The T4 Spackle protein (encoded by gene 61.3) has been thought to play a role in the inhibition of gp5 lysozyme activity and, as a consequence, in making cells infected by bacteriophage T4 resistant to later infection by T4 and closely related phages. Here we show that (1) gp61.3 is secreted into the periplasm where its N-terminal periplasm-targeting peptide is cleaved off; (2) gp61.3 forms a 1:1 complex with the lysozyme domain of gp5 (gp5Lys); (3) gp61.3 selectively inhibits the activity of gp5, but not that of T4L; (4) overexpression of gp5 causes cell lysis. We also report a crystal structure of the gp61.3-gp5Lys complex that demonstrates that unlike other known lysozyme inhibitors, gp61.3 does not interact with the active site cleft. Instead, it forms a "wall" that blocks access of an extended polysaccharide substrate to the cleft and, possibly, locks the enzyme in an "open-jaw"-like conformation making catalysis impossible.

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Primary Citation of related structures