8TED

PorX primitive orthorhombic crystal form

Summary for 8TED

• Entry DOI: 10.2210/pdb8ted/pdb
• Descriptor: Response regulator receiver protein, BROMIDE ION, CALCIUM ION, ... (5 entities in total)
• Functional Keywords: type-ix secretion system, response regulator, alkaline phosphatase, signaling protein
• Biological source: Flavobacterium johnsoniae UW101
• Total number of polymer chains: 2
• Total formula weight: 123181.83

Authors

Saran, A.,Zeytuni, N. (deposition date: 2023-07-06, release date: 2024-04-17, Last modification date: 2024-10-30)

Primary citation

Saran, A.,Kim, H.M.,Manning, I.,Hancock, M.A.,Schmitz, C.,Madej, M.,Potempa, J.,Sola, M.,Trempe, J.F.,Zhu, Y.,Davey, M.E.,Zeytuni, N.
Unveiling the molecular mechanisms of the type IX secretion system's response regulator: Structural and functional insights.
Pnas Nexus, 3:pgae316-pgae316, 2024

PubMed Abstract: The type IX secretion system (T9SS) is a nanomachinery utilized by bacterial pathogens to facilitate infection. The system is regulated by a signaling cascade serving as its activation switch. A pivotal member in this cascade, the response regulator protein PorX, represents a promising drug target to prevent the secretion of virulence factors. Here, we provide a comprehensive characterization of PorX both and . First, our structural studies revealed PorX harbors a unique enzymatic effector domain, which, surprisingly, shares structural similarities with the alkaline phosphatase superfamily, involved in nucleotide and lipid signaling pathways. Importantly, such pathways have not been associated with the T9SS until now. Enzymatic characterization of PorX's effector domain revealed a zinc-dependent phosphodiesterase activity, with active site dimensions suitable to accommodate a large substrate. Unlike typical response regulators that dimerize via their receiver domain upon phosphorylation, we found that zinc can also induce conformational changes and promote PorX's dimerization via an unexpected interface. These findings suggest that PorX can serve as a cellular zinc sensor, broadening our understanding of its regulatory mechanisms. Despite the strict conservation of PorX in T9SS-utilizing bacteria, we demonstrate that PorX is essential for virulence factors secretion in and affects metabolic enzymes secretion in the nonpathogenic , but not for the secretion of gliding adhesins. Overall, this study advances our structural and functional understanding of PorX, highlighting its potential as a druggable target for intervention strategies aimed at disrupting the T9SS and mitigating virulence in pathogenic species.

PubMed: 39139265
DOI: 10.1093/pnasnexus/pgae316

Experimental method

X-RAY DIFFRACTION (2.1 Å)