4WEP

Apo YehZ from Escerichia coli

Summary for 4WEP

• Entry DOI: 10.2210/pdb4wep/pdb
• Descriptor: Putative osmoprotectant uptake system substrate-binding protein OsmF (2 entities in total)
• Functional Keywords: periplasmic binding protein, osmoprotection, compatible solutes, glycine betaine, transport protein
• Biological source: Escherichia coli str. K-12 substr. MG1655
• Total number of polymer chains: 2
• Total formula weight: 64306.57

Authors

Kimber, M.S.,Lang, S.,Mendoza, K.,Wood, J.M. (deposition date: 2014-09-10, release date: 2015-09-16, Last modification date: 2023-09-27)

Primary citation

Lang, S.,Cressatti, M.,Mendoza, K.E.,Coumoundouros, C.N.,Plater, S.M.,Culham, D.E.,Kimber, M.S.,Wood, J.M.
YehZYXW of Escherichia coli Is a Low-Affinity, Non-Osmoregulatory Betaine-Specific ABC Transporter.
Biochemistry, 54:5735-5747, 2015

PubMed Abstract: Transporter-mediated osmolyte accumulation stimulates the growth of Escherichia coli in high-osmolality environments. YehZYXW was predicted to be an osmoregulatory transporter because (1) osmotic and stationary phase induction of yehZYXW is mediated by RpoS, (2) the Yeh proteins are homologous to the components of known osmoregulatory ABC transporters (e.g., ProU of E. coli), and (3) YehZ models based on the structures of periplasmic betaine-binding proteins suggested that YehZ retains key betaine-binding residues. The betaines choline-O-sulfate, glycine betaine, and dimethylsulfoniopropionate bound YehZ and ProX with millimolar and micromolar affinities, respectively, as determined by equilibrium dialysis and isothermal titration calorimetry. The crystal structure of the YehZ apoprotein, determined at 1.5 Å resolution (PDB ID: 4WEP ), confirmed its similarity to other betaine-binding proteins. Small and nonpolar residues in the hinge region of YehZ (e.g., Gly223) pack more closely than the corresponding residues in ProX, stabilizing the apoprotein. Betaines bound YehZ-Gly223Ser an order of magnitude more tightly than YehZ, suggesting that weak substrate binding in YehZ is at least partially due to apo state stabilization. Neither ProX nor YehZ bound proline. Assays based on osmoprotection or proline auxotrophy failed to detect YehZYXW-mediated uptake of proline, betaines, or other osmolytes. However, transport assays revealed low-affinity glycine betaine uptake, mediated by YehZYXW, that was inhibited at high salinity. Thus, YehZYXW is a betaine transporter that shares substrate specificity, but not an osmoregulatory function, with homologues like E. coli ProU. Other work suggests that yehZYXW may be an antivirulence locus whose expression promotes persistent, asymptomatic bacterial infection.

PubMed: 26325238
DOI: 10.1021/acs.biochem.5b00274

Experimental method

X-RAY DIFFRACTION (1.5 Å)