Interactions of bacterial lipopolysaccharide with microtubule proteins.
Bacterial LPS is a potent stimulator of immune cells, but its mechanisms are unknown. A possible role for microtubules in LPS actions has been indicated by previous findings that the microtubule-active agent, taxol, can mimic some effects of LPS in macrophages from normal strains of mice, but not from genetically LPS-hyporesponsive strains. In this report we demonstrate that isolated microtubules from mouse brain can bind LPS in vitro. LPS and tubulin coeluted through a gel filtration column, and LPS was cross-linked to microtubule proteins with an iodinatable, photoreactive agent, sulfosuccinimidyl 2-(p-azidosalicylamido) ethyl-1,3'-dithiopropionate. beta-Tubulin and microtubule-associated protein-2 (MAP), a predominant MAP in the brain, bound LPS specifically. Cross-linking was inhibited by an excess of unlabeled LPS or partially by unlabeled lipid A, but not by 2 M NaCl. Under the same conditions, neither myosin nor soybean trypsin inhibitor was labeled by the photoaffinity LPS probe, nor did these proteins compete for binding of LPS to beta-tubulin. These findings support the hypothesis that the microtubule network could be an intracellular target for LPS, and suggest further that a beta-tubulin-associated MAP could have an important role in LPS actions.
Ding
A
A
Beatrice and Samuel A. Seaver Laboratory, Department of Medicine, Cornell University Medical College, New York, NY 10021.
Sanchez
E
E
Tancinco
M
M
Nathan
C
C
D000345:Affinity Labels; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D066298:In Vitro Techniques; D008070:Lipopolysaccharides; D008274:Magnesium / Q000494:pharmacology; D051379:Mice; D008809:Mice, Inbred C3H; D008868:Microtubule Proteins / Q000187:drug effects*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D014404:Tubulin / Q000378:metabolism
D000345:Affinity Labels; D008070:Lipopolysaccharides; D008868:Microtubule Proteins; D008869:Microtubule-Associated Proteins; D014404:Tubulin; D012965:Sodium Chloride; D008274:Magnesium; D002118:Calcium