| Autor: |
Whitney JC; Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada., Colvin KM, Marmont LS, Robinson H, Parsek MR, Howell PL |
| Jazyk: |
angličtina |
| Zdroj: |
The Journal of biological chemistry [J Biol Chem] 2012 Jul 06; Vol. 287 (28), pp. 23582-93. Date of Electronic Publication: 2012 May 17. |
| DOI: |
10.1074/jbc.M112.375378 |
| Abstrakt: |
High cellular concentrations of bis-(3',5')-cyclic dimeric guanosine mono-phosphate (c-di-GMP) regulate a diverse range of phenotypes in bacteria including biofilm development. The opportunistic pathogen Pseudomonas aeruginosa produces the PEL polysaccharide to form a biofilm at the air-liquid interface of standing cultures. Among the proteins required for PEL polysaccharide production, PelD has been identified as a membrane-bound c-di-GMP-specific receptor. In this work, we present the x-ray crystal structure of a soluble cytoplasmic region of PelD in its apo and c-di-GMP complexed forms. The structure of PelD reveals an N-terminal GAF domain and a C-terminal degenerate GGDEF domain, the latter of which binds dimeric c-di-GMP at an RXXD motif that normally serves as an allosteric inhibition site for active diguanylate cyclases. Using isothermal titration calorimetry, we demonstrate that PelD binds c-di-GMP with low micromolar affinity and that mutation of residues involved in binding not only decreases the affinity of this interaction but also abrogates PEL-specific phenotypes in vivo. Bioinformatics analysis of the juxtamembrane region of PelD suggests that it contains an α-helical stalk region that connects the soluble region to the transmembrane domains and that similarly to other GAF domain containing proteins, this region likely forms a coiled-coil motif that mediates dimerization. PelD with Alg44 and BcsA of the alginate and cellulose secretion systems, respectively, collectively constitute a group of c-di-GMP receptors that appear to regulate exopolysaccharide assembly at the protein level through activation of their associated glycosyl transferases. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
|
