The product included a six-histidine tag fused to the C-terminal end of the protein. To construct plasmid pBBR-yqiC, a 1210 bp fragment containing yqiC gene and flanking regions from S. Typhimurium Selleckchem Ibrutinib was amplified by PCR using the primers 5′-GGCTTCAATGGTCACGGTAA-3′ and 5′-GCAATATGGACGAGGAGCATC-3′. The resulting fragment was then cloned into the EcoRI site of the broad-host-range plasmid pBBR1MCS1 [33]. Expression and Purification of Recombinant Protein pET24D plasmid encoding the sequence of yqiC was transformed in E. coli BL21 (lambda DE3). The cells were grown in LB at 37°C to an OD 600 of 0.5 and induced with 1 mM

isopropyl β-D thiogalactoside (IPTG) for 4 h. Cells were harvested by centrifugation Selleckchem Vemurafenib at 3000 × g for 20 min, resuspended in binding buffer (Qiagen), and disrupted by sonication with a probe tip sonicator. Total cell lysate was centrifuged at 14000 × g for 30 min to remove non-soluble protein,

cell debris, and unbroken cells. Binding and elution from nickel nitrilotriacetic acid-agarose resin were carried out under native conditions according to the manufacturer’s instructions (Qiagen). Eluted proteins were dialyzed against phosphate-buffered saline (pH 7.4). Proteins were assayed with a Coomassie blue-based staining solution. Vesicle Preparation Phospholipids were purchased from Avanti Polar Lipids (Birmingham, AL) and from Sigma. L-α-dipalmitoylphosphatidylcholine (DPPC) and L- α-dipalmitoylphosphatidic acid (DPPA) were cosolubilized in chloroform in different molar ratios, dried under N2, resuspended in buffer

FER 50 mM Tris-HCl pH 8.0 or 50 mM sodium acetate pH 4.0 and sonicated to yield small unilamellar vesicles (SUV). Chemical Cross-Linking Purified YqiC was cross-linked with ethylene glycol bis (succinimidylsuccinate) (EGS) (Sigma) used at concentrations of 0.5, 1.0, and 5.0 mM. The reactions were carried out for 30 min at room temperature in phosphate-buffered saline and stopped by addition of 50 mM Tris-HCl, pH 8.0. Cross-linked products were analyzed by SDS-PAGE. Determination of the Molecular Weight by Static Light Scattering The average molecular weight (Mw) of YqiC was determined on a Precision Detector PD2010 light scattering instrument tandemly connected to a high-performance liquid chromatography system and an LKB 2142 differential refractometer. The sample was loaded on a Superdex 75 column and eluted with PBS buffer. The 90° light scattering and refractive index signals of the eluting material were analyzed with Discovery32 software, supplied by Precision Detector. The 90° light scattering detector was calibrated using bovine serum albumin (66.5 kDa) as a standard. Circular Dichroism Spectroscopy The circular dichroism (CD) spectra of YqiC in the far-UV region (250-200 nm) were measured on a Jasco J-810 spectrophotometer using quartz cuvettes with a path length of 0.1 cm.