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PDBsum entry 4q25
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Unknown function
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PDB id
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4q25
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References listed in PDB file
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Key reference
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Title
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Crystal structure of phou from pseudomonas aeruginosa, A negative regulator of the pho regulon.
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Authors
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S.J.Lee,
Y.S.Park,
S.J.Kim,
B.J.Lee,
S.W.Suh.
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Ref.
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J Struct Biol, 2014,
188,
22-29.
[DOI no: ]
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PubMed id
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Abstract
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In Escherichia coli, seven genes (pstS, pstC, pstA, pstB, phoU, phoR, and phoB)
are involved in sensing environmental phosphate (Pi) and controlling the
expression of the Pho regulon. PhoU is a negative regulator of the Pi-signaling
pathway and modulates Pi transport through Pi transporter proteins (PstS, PstC,
PstA, and PstB) through the two-component system PhoR and PhoB. Inactivation of
PhoY2, one of the two PhoU homologs in Mycobacterium tuberculosis, causes
defects in persistence phenotypes and increased susceptibility to antibiotics
and stresses. Despite the important biological role, the mechanism of PhoU
function is still unknown. Here we have determined the crystal structure of PhoU
from Pseudomonas aeruginosa. It exists as a dimer in the crystal, with each
monomer consisting of two structurally similar three-helix bundles. Our
equilibrium sedimentation measurements support the reversible monomer-dimer
equilibrium model in which P. aeruginosa PhoU exists in solution predominantly
as dimers, with monomers in a minor fraction, at low protein concentrations. The
dissociation constant for PhoU dimerization is 3.2×10(-6)M. The overall
structure of P. aeruginosa PhoU dimer resembles those of Aquifex aeolicus PhoU
and Thermotoga maritima PhoU2. However, it shows distinct structural features in
some loops and the dimerization pattern.
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