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The main terminal branch (MTB) of the general secretory pathway is used by a wide variety of Gram- bacteria to transport exoproteins from the periplasm to the outside milieu. Recent work has led to the identification of the function of two of its 14 (or more) components: an enzyme with type-IV prepilin peptidase activity and a chaperone-like protein(More)
Type II protein secretion systems (T2SS) are molecular machines that promote specific transport of folded periplasmic proteins in Gram-negative bacteria, across a dedicated channel in the outer membrane. Secreted substrates, released to the milieu or displayed on the cell surface, contribute to bacterial adaptation to a range of habitats, from deep-sea(More)
An Escherichia coli strain containing a signal sequence mutation in the periplasmic maltose-binding protein (MBP) (malE18-1) and a point mutation in the soluble export factor SecB (secBL75Q) is completely defective in export of MBP and unable to grow on maltose (Mal- phenotype). We isolated 95 spontaneous Mal+ revertants and characterized them genetically.(More)
The closely related bacterial type II secretion (T2S) and type IV pilus (T4P) systems are sophisticated machines that assemble dynamic fibers promoting protein transport, motility, or adhesion. Despite their essential role in virulence, the molecular mechanisms underlying helical fiber assembly remain unknown. Here, we use electron microscopy and flexible(More)
Escherichia coli K-12, the most widely used laboratory bacterium, does not secrete proteins into the extracellular medium under standard growth conditions, despite possessing chromosomal genes encoding a putative type II secretion machinery (secreton). We show that in wild-type E.coli K-12, divergent transcription of the two operons in the main chromosomal(More)
Protein secretion systems in prokaryotes are increasingly shifting from being considered as experimental models for 'more complex' processes (i.e. eukaryotes) to being a major source of key biological questions in their own right. The pathways by which proteins move between compartments or insert into membranes in prokaryotic cells are certainly less(More)
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes hemorrhagic colitis and hemolytic uremic syndrome (HUS) by colonizing the gut mucosa and producing Shiga toxins (Stx). The only factor clearly demonstrated to play a role in EHEC adherence to intestinal epithelial cells is intimin, which binds host cell integrins and nucleolin, as well as a receptor(More)
Systematic sequencing of the Escherichia coli K-12 chromosome (GenBank entry U18997) has revealed the presence of an apparently complete operon of genes (the gspC-0 operon) similar to genes coding for components of the main terminal branch of the general secretory pathway (e.g., the Klebsiella oxytoca pulC-0 pullulanase secretion operon) and to related(More)
The chromosome of Escherichia coli K-12 contains a putative gene, yheB (chiA), at centisome 74.7, whose product shows sequence similarity with chitinases of bacterial and viral origin. We cloned the chiA (yheB) gene and demonstrated that it codes for a 94.5 kDa periplasmic protein with endochitinase/lysozyme activity. Under standard laboratory growth(More)
In Gram-negative bacteria, type II secretion systems (T2SS) assemble inner membrane proteins of the major pseudopilin PulG (GspG) family into periplasmic filaments, which could drive protein secretion in a piston-like manner. Three minor pseudopilins PulI, PulJ and PulK are essential for protein secretion in the Klebsiella oxytoca T2SS, but their molecular(More)