6NDP image
Entry Detail
PDB ID:
6NDP
Title:
Crystal structure of the dark-adapted full-length bacteriophytochrome XccBphP mutant L193Q from Xanthomonas campestris
Biological Source:
PDB Version:
Deposition Date:
2018-12-14
Release Date:
2019-12-18
Method Details:
Experimental Method:
Resolution:
3.89 Å
R-Value Free:
0.27
R-Value Work:
0.21
R-Value Observed:
0.21
Space Group:
P 43 21 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Bacteriophytochrome
Mutations:L193Q
Chain IDs:A, B
Chain Length:640
Number of Molecules:2
Biological Source:Xanthomonas campestris pv. campestris (strain 8004)
Ligand Molecules
Primary Citation
Pr-favoured variants of the bacteriophytochrome from the plant pathogen Xanthomonas campestris hint on light regulation of virulence-associated mechanisms.
Febs J. 288 5986 6002 (2021)
PMID: 33864705 DOI: 10.1111/febs.15883

Abstact

Red/far-red light-sensing bacteriophytochrome photoreceptor (BphP) pathways play key roles in bacterial physiology and ecology. These bilin-binding proteins photoswitch between two states, Pr (red absorbing) and Pfr (far-red absorbing). The isomerization of the chromophore and the downstream structural changes result in the light signal transduction. The agricultural pathogen Xanthomonas campestris pv. campestris (Xcc) code for a single bathy-like type BphP (XccBphP), previously shown to negatively regulate several light-mediated biological processes involved in virulence. Here, we generated three different full-length variants with single amino acid changes within its GAF domain that affect the XccBphP photocycle favouring its Pr state: L193Q, L193N and D199A. While D199A recombinant protein locks XccBphP in a Pr-like state, L193Q and L193N exhibit a significant enrichment of the Pr form in thermal equilibrium. The X-ray crystal structures of the three variants were solved, resembling the wild-type protein in the Pr state. Finally, we studied the effects of altering the XccBphP photocycle on the exopolysaccharide xanthan production and stomatal aperture assays as readouts of its bacterial signalling pathway. Null-mutant complementation assays show that the photoactive Pr-favoured XccBphP variants L193Q and L193N tend to negatively regulate xanthan production in vivo. In addition, our results indicate that strains expressing these variants also promote stomatal apertures in challenged plant epidermal peels, compared to wild-type Xcc. The findings presented in this work provide new evidence on the Pr state of XccBphP as a negative regulator of the virulence-associated mechanisms by light in Xcc.

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Primary Citation of related structures