2IYN

The co-factor-induced pre-active conformation in PhoB

Summary for 2IYN

• Entry DOI: 10.2210/pdb2iyn/pdb
• Related: 1B00 1GXP 1GXQ 1QQI 1ZES
• Descriptor: PHOSPHATE REGULON TRANSCRIPTIONAL REGULATORY PROTEIN PHOB, MAGNESIUM ION (3 entities in total)
• Functional Keywords: transcription, transcription factor, phosphate transport, activator, sensory transduction, phosphate regulation, two-component regulatory system, alpha/beta doubly-wound fold
• Biological source: ESCHERICHIA COLI
• Total number of polymer chains: 3
• Total formula weight: 43620.19

Authors

Sola, M.,Drew, D.L.,Blanco, A.G.,Gomis-Ruth, F.X.,Coll, M. (deposition date: 2006-07-19, release date: 2006-08-30, Last modification date: 2024-05-08)

Primary citation

Sola, M.,Drew, D.L.,Blanco, A.G.,Gomis-Ruth, F.X.,Coll, M.
The Cofactor-Induced Pre-Active Conformation in Phob.
Acta Crystallogr.,Sect.D, 62:1046-, 2006

PubMed Abstract: PhoB is an Escherichia coli transcription factor from a two-component signal transduction system that is sensitive to limiting environmental phosphate conditions. It consists of an N-terminal receiver domain (RD) and a C-terminal DNA-binding domain. The protein is activated upon phosphorylation at the RD, an event that depends on Mg(2+) binding. The structure of PhoB RD in complex with Mg(2+) is presented, which shows three protomers in the asymmetric unit that interact across two different surfaces. One association is symmetric and has been described as a non-active dimerization contact; the other involves the alpha4-beta5-alpha5 interface and recalls the contact found in activated PhoB. However, here this last interaction is not perfectly symmetric and helix alpha4, which in the activated molecule undergoes a helical shift, becomes strongly destabilized in one of the interacting monomers. All protomers bind the cation in a similar manner but, interestingly, at the prospective binding site for the phosphate moiety the side chains of either Glu88 (in helix alpha4) or Trp54 alternate and interact with active-site atoms. When Glu88 is inside the cavity, helix alpha4 is arranged similarly to the unliganded wild-type structure. However, if Trp54 is present, the helix loses its contacts with the active-site cavity and vanishes. Accordingly, the presence of Trp54 in the active site induces a flexible state in helix alpha4, potentially allowing a helical shift that phosphorylation would eventually stabilize.

PubMed: 16929106
DOI: 10.1107/S0907444906024541

Experimental method

X-RAY DIFFRACTION (2.08 Å)