6TO6 image
Entry Detail
PDB ID:
6TO6
Keywords:
Title:
Solution structure of the modulator of repression (MOR) of the temperate bacteriophage TP901-1 from Lactococcus lactis
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2019-12-11
Release Date:
2020-08-19
Method Details:
Experimental Method:
Conformers Calculated:
80
Conformers Submitted:
20
Selection Criteria:
NULL EMARK:
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:MOR
Chain IDs:A
Chain Length:74
Number of Molecules:1
Biological Source:Lactococcus phage TP901-1
Ligand Molecules
Primary Citation
Revealing the mechanism of repressor inactivation during switching of a temperate bacteriophage.
Proc.Natl.Acad.Sci.USA 117 20576 20585 (2020)
PMID: 32788352 DOI: 10.1073/pnas.2005218117

Abstact

Temperate bacteriophages can enter one of two life cycles following infection of a sensitive host: the lysogenic or the lytic life cycle. The choice between the two alternative life cycles is dependent upon a tight regulation of promoters and their cognate regulatory proteins within the phage genome. We investigated the genetic switch of TP901-1, a bacteriophage of Lactococcus lactis, controlled by the CI repressor and the modulator of repression (MOR) antirepressor and their interactions with DNA. We determined the solution structure of MOR, and we solved the crystal structure of MOR in complex with the N-terminal domain of CI, revealing the structural basis of MOR inhibition of CI binding to the DNA operator sites. 15N NMR Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion and rotating frame R1ρ measurements demonstrate that MOR displays molecular recognition dynamics on two different time scales involving a repacking of aromatic residues at the interface with CI. Mutations in the CI:MOR binding interface impair complex formation in vitro, and when introduced in vivo, the bacteriophage switch is unable to choose the lytic life cycle showing that the CI:MOR complex is essential for proper functioning of the genetic switch. On the basis of sequence alignments, we show that the structural features of the MOR:CI complex are likely conserved among a larger family of bacteriophages from human pathogens implicated in transfer of antibiotic resistance.

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