SecA undergoes conformational changes during translocation, inserting domains into and across the membrane or enhancing the protease resistance of these domains. We now show that some SecA bound at SecYEG is accessible from the periplasm to a membrane-impermeant probe in cells with a permeabilized outer membrane but an intact plasma membrane.

Transcription of the fecABCDE ferric citrate transport genes of Escherichia coli K-12 is initiated by a signaling cascade from the cell surface into the cytoplasm. FecR receives the signal in the periplasm from the outer membrane protein FecA loaded with ferric citrate, transmits the signal across the cytoplasmic membrane, and converts FecI in the cytoplasm to an active sigma factor. In this st...

Escherichia coli heat-labile enterotoxin (LT) consists of an A subunit and five B subunits. These subunits oligomerize into an assembled holotoxin within the periplasm. Structural analysis of LT has revealed that the A subunit interacts with the B subunit through its carboxy terminus. This indicates that the carboxy-terminal portion of the protein is required for assembly of holotoxin in the pe...

Electron microscopic immunogold labeling experiments were performed with ultrathin sections of plasmolyzed cells of Alcaligenes eutrophus and "whole-mount" samples of spheroplasts and protoplasts. They demonstrated that antigenic determinants of the membrane-bound hydrogenase are exposed, at the outside of the cytoplasmic membrane, to the periplasm.

A lysozyme-osmotic shock method is described for fractionation of Alcaligenes faecalis which uses glucose to adjust osmotic strength and multiple osmotic shocks. During phenylethylamine-dependent growth, aromatic amine dehydrogenase, azurin, and a single cytochrome c were localized in the periplasm. Their induction patterns are different from those for the related quinoprotein methylamine dehyd...

BACKGROUND The pH of the human gastric mucosa varies around 2.5 so that only bacteria with strong acidic stress tolerance can colonize it. The ulcer causing Helicobacter pylori thrives in the gastric mucosa. We analyse the roles of the key outer membrane protein OMPLA in its roles in acid tolerance. RESULTS The homology model of Helicobacter pylori outer membrane phospholipase A (OMPLA) revea...