2jb9

File:2jb9.jpg

spinqualitylabelsall models 2jb9, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

PHOB RESPONSE REGULATOR RECEIVER DOMAIN CONSTITUTIVELY-ACTIVE DOUBLE MUTANT D10A AND D53E.

OverviewOverview

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.

About this StructureAbout this Structure

2JB9 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

ReferenceReference

The X-ray crystal structures of two constitutively active mutants of the Escherichia coli PhoB receiver domain give insights into activation., Arribas-Bosacoma R, Kim SK, Ferrer-Orta C, Blanco AG, Pereira PJ, Gomis-Ruth FX, Wanner BL, Coll M, Sola M, J Mol Biol. 2007 Feb 16;366(2):626-41. Epub 2006 Nov 14. PMID:17182055

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