Localization and assembly into the Escherichia coli envelope of a protein required for entry of colicin A.
AUTOR(ES)
Bourdineaud, J P
RESUMO
Mutations in tolQ, previously designated fii, render cells tolerant to high concentrations of colicin A. In addition, a short deletion in the amino-terminal region of colicin A (amino acid residues 16 to 29) prevents its lethal action, although this protein can still bind the receptor and forms channels in planar lipid bilayers in vitro. These defects in translocation across the outer membrane in the tolQ cells or the colicin A mutant cannot be bypassed by osmotic shock. The TolQ protein, which is constitutively expressed at a low level, was studied in recombinant plasmid constructs allowing the expression of various TolQ fusion proteins under the control of the inducible caa promoter. The TolQ protein was thus "tagged" with an epitope from the colicin A protein for which a monoclonal antibody is available. A fusion protein containing the entire TolQ protein plus the 30 N-terminal residues of colicin A was shown to complement the tolQ mutation. Pulse-chase labeling followed by gradient fractionation indicated that the bulk of the overproduced fusion protein was rapidly incorporated into the inner membrane, with small amounts localized to regions corresponding to the attachment sites between inner and outer membranes and to the outer membrane itself. However, most of the protein was rapidly degraded, leaving only that localized to the attachment sites and the outer membrane remaining at very late times of chase.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=209921Documentos Relacionados
- Maturation and localization of the TolB protein required for colicin import.
- The Escherichia coli FIS protein is not required for the activation of tyrT transcription on entry into exponential growth.
- The YXXL Sequences of a Transmembrane Protein of Bovine Leukemia Virus Are Required for Viral Entry and Incorporation of Viral Envelope Protein into Virions
- Colicin cleavage by OmpT protease during both entry into and release from Escherichia coli cells.
- Membrane topology of the Escherichia coli TolR protein required for cell envelope integrity.