0) using Quick Spin protein column (Roche, Indianapolis, IN). The protein samples were separated on sodium dodecyl sulfate-polyacrylamide
gel electrophoresis (SDS-PAGE) (Novex TG and Tris-acetate NuPAGE gels, Invitrogen) and two-dimensional gel electrophoresis with ReadyStrip IPG Strips and Criterion pre-cast gel (BioRad). Protein treatment, obtaining peptide mass fingerprints, and identifying peptides were performed by the Mass Spectrometry/Proteomics VX-765 solubility dmso Facility at Johns Hopkins School of Medicine (http://www.hopkinsmedicine.org/msf/). The Coomassie-stained protein bands were excised from the gel and in-gel digested by trypsin. After the desalting process, a mass list of peptides was obtained for each protein using a matrix-assisted laser desorption/ionization-time-of-flight mass spectrometer (Voyager DE-STR). ms-fit (http://prospector.ucsf.edu/prospector/cgi-bin/msform.cgi?form=msfitstandard) and mascot (http://www.matrixscience.com) software were used to identify the proteins. To verify see more protein–protein interaction
(i.e. FimH–ATP synthase β-subunit), purified FimCH (5 μg) was mixed with 200 μg HBMEC lysates at 4 °C for 3 h to allow the binding complex to form between FimH and ATP synthase β-subunit of the HBMEC lysates. For a negative control, 2.5 μg FimC protein was used to adjust for molar ratio with FimCH. To pull-down the FimH–ATP synthase β-subunit complex, 10 μg of affinity-purified anti-FimH rabbit serum or 5 μg of anti-ATP synthase β-subunit antibody (BD Biosciences) was added and incubated overnight at 4 °C. Protein A agarose beads were incubated with the protein– antibody mixture at 4 °C for 3 h, and then precipitated by centrifugation (5000 g, for 1 min). In the case of the pull-down with the antibiotin antibody, 10 μg of antibiotin serum was used. Protein complexes were separated by SDS-PAGE using Novex TG gel and the separated proteins were transferred to polyvinylidene fluoride membranes. The membranes were blocked with TBST [20 mM Tris (pH 7.5), 150 mM NaCl, 0.1% Tween-20] containing 5% bovine serum albumin for 1 h at room temperature and incubated with anti-ATP
synthase β-subunit and FimH antibodies overnight at 4 °C. The blots were washed with TBST and incubated old with a HRP-conjugated anti-mouse or -rabbit IgG antibody (1 : 5000 dilution, Cell Signaling Technology) in 5% skim milk-TBST for 1 h at room temperature. For probing biotinylated proteins, membranes were blocked with 5% skim milk-TBST and incubated with HRP-conjugated antibiotin antibody (Cell Signaling Technology) at room temperature for 1 h. The blots were washed with TBST and developed with ECL Western detection reagent (Amersham Biosciences). We have previously shown that type 1 fimbriae contribute to the binding of meningitis-causing E. coli K1 strain RS 218 to HBMEC and the binding was significantly reduced by α-methyl mannose, but α-methyl mannose did not decrease the HBMEC binding of E.