This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Rocque, W J Articles by McGroarty, E J Search for Related Content PubMed PubMed Citation Articles by Rocque, W J Articles by McGroarty, E J

 Previous Article  |  Next Article 

J Bacteriol. 1987 September; 169(9): 4003-4010

Lipopolysaccharide tightly bound to porin monomers and trimers from Escherichia coli K-12.

ABSTRACT

Lipopolysaccharide (LPS) bound to isolated porin was detected on polyacrylamide gels by using a carbohydrate-specific silver stain and on Western blots by using anti-lipid A monoclonal antibodies. Porin was isolated from Escherichia coli JF733 (Ra chemotype) and D21f2 (Re chemotype). Isolated porin was separated from loosely associated LPS by polyacrylamide gel electrophoresis (PAGE) in sodium dodecyl sulfate (SDS). Unheated porin traveled on gels as aggregates, presumably trimers, with an apparent molecular weight of 78,000 to 83,000. After heating to 100 degrees C for 2 min in SDS, the porin traveled as a monomer with a molecular weight of 36,000. The unheated, high-molecular-weight trimer band reacted in the gel with the carbohydrate-specific silver stain, while the heated monomer band showed no staining. In contrast, lipid A-specific monoclonal antibodies showed reactivity on Western blots to the 36,000-molecular-weight band but not to the trimer. Finally, both monomer and trimer bands were isolated from gels and rerun by SDS-PAGE. LPS was released from the trimer preparation when the sample was heated, but the monomer band that was formed by heating the trimer isolate still reacted with anti-lipid A antibodies. Quantitative Limulus amebocyte lysate analysis revealed an approximately equal molar ratio of LPS to protein in the electroeluted porin monomer. Thus, some but not all of the LPS could be released from trimer complexes by boiling in SDS. The isolated monomer did not release more LPS on boiling in SDS a second time but still had LPS tightly bound, as detected by lipid A-specific monoclonal antibodies.

This article has been cited by other articles:

• Nikaido, H. (2003). Molecular Basis of Bacterial Outer Membrane Permeability Revisited. Microbiol. Mol. Biol. Rev. 67: 593-656 [Abstract] [Full Text]  
• Taylor, R., Burgner, J. W., Clifton, J., Cramer, W. A. (1998). Purification and Characterization of Monomeric Escherichia coli Vitamin B12 Receptor with High Affinity for Colicin E3. J. Biol. Chem. 273: 31113-31118 [Abstract] [Full Text]  
• Cosma, C. L., Crotwell, M. D., Burrows, S. Y., Silhavy, T. J. (1998). . J. Bacteriol. 180: 3120-3130 [Abstract] [Full Text]