Proper mutation was confirmed by DNA sequencing. To create a recombinant truncated HBP35 protein (M135-P344) with an N-terminal histidine-tag overexpression system, a 0.66-kb PCR fragments were amplified using forward primer MS25 and backward primer MS22, and then cloned into pET30Ek/LIC vector, resulting in pKD753. Expression and purification of P. gingivalis recombinant HBP35 proteins E. coli BL21(DE3)pLysS harboring pKD750, pKD751, pKD752 or pKD753 was cultured in LB medium containing 100 μg/ml of Ap at 37°C to OD600 of 0.4-0.6, and then IPTG was added to the

culture at 1 mM, followed by an additional 3-h incubation. The cells were harvested, suspended in buffer A (50 mM NaH2PO4 [pH 8.0], learn more 500 mM NaCl, 10 mM imidazole) and then disrupted with a French Press. The mixture was centrifuged at 3,000 × g for 15 min to IWR-1 datasheet separate the inclusion body fraction (pellet) from the soluble fraction (supernatant). The supernatant was

loaded onto a pre-equilibrated Ni2+-NTA agarose column (Invitrogen) buy Stattic of 2 ml in bed volume and incubated at 4°C for 30 min. The column was washed three times with buffer B (50 mM NaH2PO4 [pH 8.0], 500 mM NaCl, 20 mM imidazole) and the bound protein was eluted with 10 ml of elution buffer (50 mM NaH2PO4 [pH 8.0], 500 mM NaCl, 250 mM imidazole) as 1-ml fractions. The fractions were analyzed by SDS-PAGE. The pure fractions were pooled and then dialyzed against milliQ water and stored at -20°C until further use. N-terminal amino acid sequencing (Edman sequencing) of the purified rHBP35 protein with the C-terminal histidine-tag was carried out using the service facility in CSIRO (Melbourne, Australia). Interleukin-3 receptor Gel electrophoresis and immunoblot analysis SDS-PAGE was performed according to the method of Laemmli [32]. Protease inhibitors (leupeptin and TLCK) were added to Laemmli solubilizing buffer to avoid proteolysis by endogenous proteases. The gels were stained with 0.1% Coomassie Brilliant Blue R-250 (CBB). For immunoblotting,

proteins on SDS-PAGE gels were electrophoretically transferred onto polyvinylidene fluoride (PVDF) membranes (Immobilon P; Millipore) as described previously [33]. The blotted membranes were detected with an anti-HBP35 polyclonal antibody [6]. Preparation of P. gingivalis subcellular fractions P. gingivalis cells were harvested from 400 ml of fully-grown culture by centrifugation at 10,000 × g for 30 min at 4°C, washed twice with 10 mM HEPES-NaOH (pH 7.4) containing 0.15 M NaCl, and resuspended in 20 ml of HEPES containing 0.1 mM TLCK, 0.1 mM leupeptin and 0.2 mM PMSF. The cells were disrupted with a French Press by three passes at 100 MPa in the presence of 25 μg/ml each of RNase and DNase. Unbroken cells were removed by centrifugation at 1,000 × g for 10 min and the supernatant was subjected to ultracentrifugation at 100,000 × g for 60 min.