1r48
Solution structure of the C-terminal cytoplasmic domain residues 468-497 of Escherichia coli protein ProP
Structural highlights
FunctionPROP_ECOLI Proton symporter that senses osmotic shifts and responds by importing osmolytes such as proline, glycine betaine, stachydrine, pipecolic acid, ectoine and taurine. It is both an osmosensor and an osmoregulator which is available to participate early in the bacterial osmoregulatory response. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBacteria respond to increasing medium osmolality by accumulating organic solutes that are compatible with cellular functions. Transporter ProP of Escherichia coli, a proton symporter and a member of the major facilitator superfamily, senses osmotic shifts and responds by importing osmolytes such as glycine betaine. ProP contains a cytoplasmic, C-terminal extension that is essential for its activity. A peptide corresponding to the C-terminal extension of ProP forms a homodimeric alpha-helical coiled-coil even though some of its heptad a positions are not occupied by hydrophobic amino acid residues. Unexpectedly, amino acid replacement R488I, occurring at a heptad a position, destabilized the coiled-coil formed by the ProP peptide and attenuated the response of the intact transporter to osmotic upshifts in vivo. Thus, ProP was proposed to dimerize via an antiparallel coiled-coil. We used nuclear magnetic resonance (NMR) spectroscopy to determine the structure of the synthetic peptide corresponding to residues 468-497 of ProP. This region did form an antiparallel coil-coil in which critical residue R488 specifies the antiparallel coiled-coil orientation by forming stabilizing salt-bridges. Charged residues (both acidic and basic) are clustered on the c/g surface of the coiled-coil whereas polar residues are distributed on the b/e surface. This causes the structure to be bent, in contrast to other known antiparallel coiled-coils (those from the hepatitis delta antigen (PDB ID code 1A92) and the bovine F(1) ATPase inhibitor protein (PDB ID code 1HF9)). The coiled-coil and its possible importance for osmosensing are discussed. Solution structure of the C-terminal antiparallel coiled-coil domain from Escherichia coli osmosensor ProP.,Zoetewey DL, Tripet BP, Kutateladze TG, Overduin MJ, Wood JM, Hodges RS J Mol Biol. 2003 Dec 12;334(5):1063-76. PMID:14643666[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References | ||||||||||||||||||
