2JB9

PhoB response regulator receiver domain constitutively-active double mutant D10A and D53E.

Summary for 2JB9

• Entry DOI: 10.2210/pdb2jb9/pdb
• Related: 1B00 1GXP 1GXQ 1QQI 1ZES 2IYN 2JBA
• Descriptor: PHOSPHATE REGULON TRANSCRIPTIONAL REGULATORY PROTEIN PHOB (2 entities in total)
• Functional Keywords: sensory transduction, dna-binding, two-component regulatory system, gene regulation, phosphate transport, activation of the pho regulon, transcription
• Biological source: ESCHERICHIA COLI
• Cellular location: Cytoplasm: P0AFJ5
• Total number of polymer chains: 2
• Total formula weight: 28971.54

Authors

Ferrer-Orta, C.,Arribas-Bosacoma, R.,Kim, S.-K.,Blanco, A.G.,Pereira, P.J.B.,Gomis-Ruth, F.X.,Wanner, B.L.,Coll, M.,Sola, M. (deposition date: 2006-12-05, release date: 2007-01-04, Last modification date: 2023-12-13)

Primary citation

Arribas-Bosacoma, R.,Kim, S.-K.,Ferrer-Orta, C.,Blanco, A.G.,Pereira, P.J.B.,Gomis-Ruth, F.X.,Wanner, B.L.,Coll, M.,Sola, M.
The X-Ray Crystal Structures of Two Constitutively Active Mutants of the E. Coli Phob Receiver Domain Give Insights Into Activation
J.Mol.Biol., 366:626-, 2007

PubMed Abstract: The PhoR/PhoB two-component system is a key regulatory protein network enabling Escherichia coli to respond to inorganic phosphate (Pi) starvation conditions by turning on Pho regulon genes for more efficient Pi uptake and use of alternative phosphorus sources. Under environmental Pi depletion, the response regulator (RR) component, PhoB, is phosphorylated at the receiver domain (RD), a process that requires Mg(2+) bound at the active site. Phosphorylation of the RD relieves the inhibition of the PhoB effector domain (ED), a DNA-binding region that binds to Pho regulon promoters to activate transcription. The molecular details of the activation are proposed to involve dimerization of the RD and a conformational change in the RD detected by the ED. The structure of the PhoB RD shows a symmetrical interaction involving alpha1, loop beta5alpha5 and N terminus of alpha5 elements, also seen in the complex of PhoB RD with Mg(2+), in which helix alpha4 highly increases its flexibility. PhoB RD in complex with Mg(2+) and BeF(3) (an emulator of the phosphate moiety) undergoes a dramatic conformational change on helix alpha4 and shows another interaction involving alpha4, beta5 and alpha5 segments. We have selected a series of constitutively active PhoB mutants (PhoB(CA)) that are able to turn on the Pho regulon promoters in the absence phosphorylation and, as they cannot be inactivated, should therefore mimic the active RD state of PhoB and its functional oligomerisation. We have analysed the PhoB(CA) RD crystal structures of two such mutants, Asp53Ala/Tyr102Cys and Asp10Ala/Asp53Glu. Interestingly, both mutants reproduce the homodimeric arrangement through the symmetric interface encountered in the unbound and magnesium-bound wild-type PhoB RD structures. Besides, the mutant RD structures show a modified active site organization as well as changes at helix alpha4 that correlate with repositioning of surrounding residues, like the active-site events indicator Trp54, putatively redifining the interaction with the ED in the full-length protein.

PubMed: 17182055
DOI: 10.1016/J.JMB.2006.11.038

Experimental method

X-RAY DIFFRACTION (1.7 Å)