The Crystal Structure of UehA in Complex with Ectoine-A Comparison with Other TRAP-T Binding Proteins

JOURNAL OF MOLECULAR BIOLOGY

卷:389

Article

Lecher, Justin¹  Pittelkow, Marco²  Zobel, Silke¹  Bursy, Jan²  Boenig, Tobias²  Smits, Sander H. J.¹  Schmitt, Lutz¹  Bremer, Erhard² 

[1] Univ Dusseldorf, Inst Biochem, Univ Str 1, D-40225 Dusseldorf, Germany

[2] Univ Marburg, Dept Biol, Microbiol Lab, D-35032 Marburg, Germany

关键词: TRAP transporters;    periplasmic binding proteins;    ectoine;    compatible solutes;   

DOI  :  10.1016/j.jmb.2009.03.077

来源: Elsevier

【 摘 要 】

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 mu M, respectively) and delivers them to the TRAP-T complex. The crystal structure of UehA in complex with ectoine was determined at 2.9-angstrom 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. (C) 2009 Elsevier Ltd. All rights reserved.

【 授权许可】

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