The twin-arginine translocase (Tat) system is a recently discovered pathway which transports proteins in bacteria and chloroplasts. This system only translocates proteins with a cleavable N-terminal signal peptide with the distinctive twin-arginine (RR) motif, which is crucial to Tat function. Here, site-directed mutagenesis of the signal peptide of the Tat substrate TorA-GFP which has a triple...

A periplasmic catalase has been purified and cloned from Brucella abortus. The functional enzyme is a tetramer with a subunit molecular weight of 55,000. All evidence indicates that a typical N-terminal signal sequence is not associated with the export of this protein to the periplasm.

We demonstrated that both the A and B subunits of heat-labile enterotoxin from Escherichia coli are located in the periplasm. The toxin was shown to form aggregates in Tris-EDTA buffers which are routinely used for isolating membranes. The aggregates pellet upon centrifugation, and this may explain why several previous investigators have concluded that enterotoxin is associated with membranes.

UNLABELLED The syphilis spirochete Treponema pallidum is an important human pathogen but a highly enigmatic bacterium that cannot be cultivated in vitro. T. pallidum lacks many biosynthetic pathways and therefore has evolved the capability to exploit host-derived metabolites via its periplasmic lipoprotein repertoire. We recently reported a flavin-trafficking protein in T. pallidum (Ftp_Tp; TP0...

MexA-MexB-OprM is an efflux system in Pseudomonas aeruginosa. OprM overproduced from the cloned gene was able to complement OprM-deficient mutants but did not alter the resistance of a wild-type P. aeruginosa strain to the different antimicrobial agents tested. This suggests that OprM cannot function by itself to efflux antibiotics, including beta-lactams targeted to the periplasm.

The most frequently used approach to produce single-chain Fv fragments (scFv) and Fab in Escherichia coli is to express them in the periplasm of the bacteria. We present here an alternative procedure that uses cytoplasmic expression of soluble active scFv. This can be accomplished by using either specially engineered E. coli strains or hyperstable scFvs.