1y8s

Theoretical Model: The protein structure described on this page was determined theoretically, and hence should be interpreted with caution.

THEORETICAL MODEL OF THE PROTON-PROLINE SYMPORTER PROPTHEORETICAL MODEL OF THE PROTON-PROLINE SYMPORTER PROP

Structural highlights For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, PDBsum, ProSAT Publication Abstract from PubMed Transporter ProP of Escherichia coli, a member of the major facilitator superfamily (MFS), acts as an osmosensor and an osmoregulator in cells and after purification and reconstitution in proteoliposomes. H(+)-osmoprotectant symport via ProP is activated when medium osmolality is elevated with membrane impermeant osmolytes. The three-dimensional structure of ProP was modeled with the crystal structure of MFS member GlpT as a template. This GlpT structure represents the inward (or cytoplasm)-facing conformation predicted by the alternating access model for transport. LacZ-PhoA fusion analysis and site-directed fluorescence labeling substantiated the membrane topology and orientation predicted by this model and most hydropathy analyses. The model predicts the presence of a proton pathway within the N-terminal six-helix bundle of ProP (as opposed to the corresponding pathway found within the C-terminal helix bundle of its paralogue, LacY). Replacement of residues within the N-terminal helix bundle impaired the osmotic activation of ProP, providing the first indication that residues outside the C-terminal domain are involved in osmosensing. Some residues that were accessible from the periplasmic side, as predicted by the structural model, were more susceptible to covalent labeling in permeabilized membrane fractions than in intact bacteria. These residues may be accessible from the cytoplasmic side in structures not represented by our current model, or their limited exposure in vivo may reflect constraints on transporter structure that are related to its osmosensory mechanism. A structural model for the osmosensor, transporter, and osmoregulator ProP of Escherichia coli.,Wood JM, Culham DE, Hillar A, Vernikovska YI, Liu F, Boggs JM, Keates RA Biochemistry. 2005 Apr 19;44(15):5634-46. PMID:15823022 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

spinqualitylabelsall models 1y8s Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image