title: Bacterial peptidoglycan binds to tubulin.
abstract: A search for cellular binding proteins for peptidoglycan (PGN), a CD14- and TLR2-dependent macrophage activator from Gram-positive bacteria, using PGN-affinity chromatography and N-terminal micro-sequencing, revealed that tubulin was a major PGN-binding protein in mouse macrophages. Tubulin also co-eluted with PGN from anti-PGN vancomycin affinity column and bound to PGN coupled to agarose. Tubulin-PGN binding was preferential under the conditions that promote tubulin polymerization, required macromolecular PGN, was competitively inhibited by soluble PGN and tubulin, did not require microtubule-associated proteins, and had an affinity of 100-150 nM. By contrast, binding of tubulin to lipopolysaccharide (LPS) had 2-3 times lower affinity, faster kinetics of binding, and showed positive cooperativity. PGN enhanced tubulin polymerization in the presence of 4 M glycerol, but in the absence of glycerol, both PGN and LPS decreased microtubule polymerization. These results indicate that tubulin is a major PGN-binding protein and that PGN modulates tubulin polymerization.
authors.affiliation: Northwest Center for Medical Education, Indiana University School of Medicine, Gary, 46408, USA. rdziar@iunhaw1.iun.indiana.edu
authors.forename: R
authors.initials: R
authors.lastname: Dziarski
authors.forename: M M
authors.initials: MM
authors.lastname: Rasenick
authors.forename: D
authors.initials: D
authors.lastname: Gupta
mesh_terms: D000818:Animals; D002460:Cell Line; D002846:Chromatography, Affinity; D008070:Lipopolysaccharides / Q000737:chemistry; D008248:Lysostaphin; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology; D010457:Peptidoglycan / Q000737:chemistry / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry; D011485:Protein Binding / Q000187:drug effects; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D008070:Lipopolysaccharides; D008869:Microtubule-Associated Proteins; D010457:Peptidoglycan; D011108:Polymers; D014404:Tubulin; D008248:Lysostaphin; D017239:Paclitaxel