The interaction of colicins with target cells is a paradigm for protein import. To enter cells, bactericidal colicins parasitize Escherichia coli outer membrane receptors whose physiological purpose is the import of essential metabolites. Colicins E1 and E3 initially bind to the BtuB receptor, whose beta-barrel pore is occluded by an N-terminal globular "plug". The x-ray structure of a complex ...

Molecular dynamics simulations allow a direct study of the structure and dynamics of membrane proteins and lipids. We describe the behavior of aromatic residues and lipid properties in POPE and POPC bilayer models with the Escherichia coli OmpF trimer, single alamethicin and Influenza M2 helices, 4-helix M2 bundles, and two alamethicin 6-helix channel models. The total simulation time is over 2...

Despite the growing interest in membrane proteins, their crystallization remains a major challenge. In the course of a crystallographic study on the multidrug ATP-binding cassette transporter BmrA, mass spectral analyses on samples purified with six selected detergents revealed unexpected protein contamination visible for the most part on overloaded SDS-PAGE. A major contamination from the oute...

Using a lysine-specific cleavable cross-linking reagent ethylene glycolbis(sulfosuccimidylsuccinate) (Sulfo-EGS), we studied conformational motion in the surface loops of Escherichia coli FepA during its transport of the siderophore ferric enterobactin. Site-directed mutagenesis determined that Sulfo-EGS reacted with two lysines, K332 and K483, and at least two other unidentified Lys residues i...

Yep-phi is a T7-related bacteriophage specific to Yersinia pestis, and it is routinely used in the identification of Y. pestis in China. Yep-phi infects Y. pestis grown at both 20°C and 37°C. It is inactive in other Yersinia species irrespective of the growth temperature. Based on phage adsorption, phage plaque formation, affinity chromatography, and Western blot assays, the outer membrane prot...

The DNA sequence of the ompC gene which encodes one of the outer membrane porins has been determined. The gene appears to encode a secretory precursor of OmpC protein consisting of a total of 367 amino acid residues with a signal peptide of 21 amino acid residues at its NH2-terminal end. The 5' end noncoding region including the promoter of the ompC gene is extremely [A-T]-rich, and the codon u...

Previously, an unexplained subcellular localization was reported for a functional fluorescent protein fusion to the response regulator OmpR in Escherichia coli. The pronounced regions of increased fluorescence, or foci, are dependent on OmpR phosphorylation and do not occupy fixed, easily identifiable positions, such as the poles or mid-cell. Here we show that the foci are due to OmpR-YFP (yell...

The 315-residue N-terminal T domain of colicin E3 functions in translocation of the colicin across the outer membrane through its interaction with outer membrane proteins including the OmpF porin. The first 83 residues of the T domain are known from structure studies to be disordered. This flexible translocation subdomain contains the TolB box (residues 34 to 46) that must cross the outer membr...