3FXB

Crystal structure of the ectoine-binding protein UehA

Summary for 3FXB

• Entry DOI: 10.2210/pdb3fxb/pdb
• Descriptor: TRAP dicarboxylate transporter, DctP subunit, (4S)-2-METHYL-1,4,5,6-TETRAHYDROPYRIMIDINE-4-CARBOXYLIC ACID (2 entities in total)
• Functional Keywords: periplasmic substrate binding protein, selectivity helix, transport, membrane, transport protein
• Biological source: Silicibacter pomeroyi DSS-3
• Total number of polymer chains: 2
• Total formula weight: 73269.59

Authors

Lecher, J.,Pittelkow, M.,Bursy, J.,Smits, S.H.J.,Schmitt, L.,Bremer, E. (deposition date: 2009-01-20, release date: 2009-05-26, Last modification date: 2024-10-30)

Primary citation

Lecher, J.,Pittelkow, M.,Zobel, S.,Bursy, J.,Bonig, T.,Smits, S.H.,Schmitt, L.,Bremer, E.
The crystal structure of UehA in complex with ectoine-A comparison with other TRAP-T binding proteins.
J.Mol.Biol., 389:58-73, 2009

PubMed Abstract: Substrate-binding proteins or extracellular solute receptors (ESRs) are components of both ABC (ATP binding cassette) and TRAP-T (tripartite ATP-independent periplasmic transporter). The TRAP-T system UehABC from Silicibacter pomeroyi DSS-3 imports the compatible solutes ectoine and 5-hydroxyectoine as nutrients. UehA, the ESR of the UehABC operon, binds both ectoine and 5-hydroxyectoine with high affinity (K(d) values of 1.4+/-0.1 and 1.1+/-0.1 microM, respectively) and delivers them to the TRAP-T complex. The crystal structure of UehA in complex with ectoine was determined at 2.9-A resolution and revealed an overall fold common for all ESR proteins from TRAP systems determined so far. A comparison of the recently described structure of TeaA from Halomonas elongata and an ectoine-binding protein (EhuB) from an ABC transporter revealed a conserved ligand binding mode that involves both directed and cation-pi interactions. Furthermore, a comparison with other known TRAP-T ESRs revealed a helix that might act as a selectivity filter imposing restraints on the ESRs that fine-tune ligand recognition and binding and finally might determine the selection of the cognate substrate.

PubMed: 19362561
DOI: 10.1016/j.jmb.2009.03.077

Experimental method

X-RAY DIFFRACTION (2.9 Å)