3BQA

Crystal Structure of an E.coli PhoQ Sensor Domain Mutant

Summary for 3BQA

• Entry DOI: 10.2210/pdb3bqa/pdb
• Related: 3BQ8
• Descriptor: Sensor protein phoQ, SULFATE ION (3 entities in total)
• Functional Keywords: histidine kinase sensor domain, atp-binding, inner membrane, magnesium, membrane, metal-binding, nucleotide-binding, phosphoprotein, transferase, transmembrane, two-component regulatory system, signaling protein
• Biological source: Escherichia coli
• Cellular location: Cell inner membrane ; Multi-pass membrane protein : P23837
• Total number of polymer chains: 2
• Total formula weight: 34338.77

Authors

Cheung, J.,Hendrickson, W.A.,Waldburger, C.D. (deposition date: 2007-12-19, release date: 2008-03-25, Last modification date: 2024-02-21)

Primary citation

Cheung, J.,Bingman, C.A.,Reyngold, M.,Hendrickson, W.A.,Waldburger, C.D.
Crystal Structure of a Functional Dimer of the PhoQ Sensor Domain.
J.Biol.Chem., 283:13762-13770, 2008

PubMed Abstract: The PhoP-PhoQ two-component system is a well studied bacterial signaling system that regulates virulence and stress response. Catalytic activity of the histidine kinase sensor protein PhoQ is activated by low extracellular concentrations of divalent cations such as Mg2+, and subsequently the response regulator PhoP is activated in turn through a classic phosphotransfer pathway that is typical in such systems. The PhoQ sensor domains of enteric bacteria contain an acidic cluster of residues (EDDDDAE) that has been implicated in direct binding to divalent cations. We have determined crystal structures of the wild-type Escherichia coli PhoQ periplasmic sensor domain and of a mutant variant in which the acidic cluster was neutralized to conservative uncharged residues (QNNNNAQ). The PhoQ domain structure is similar to that of DcuS and CitA sensor domains, and this PhoQ-DcuS-CitA (PDC) sensor fold is seen to be distinct from the superficially similar PAS domain fold. Analysis of the wild-type structure reveals a dimer that allows for the formation of a salt bridge across the dimer interface between Arg-50' and Asp-179 and with nickel ions bound to aspartate residues in the acidic cluster. The physiological importance of the salt bridge to in vivo PhoQ function has been confirmed by mutagenesis. The mutant structure has an alternative, non-physiological dimeric association.

PubMed: 18348979
DOI: 10.1074/jbc.M710592200

Experimental method

X-RAY DIFFRACTION (2 Å)