The cultures were diluted 1:10, plated on LB agar plates containing 10 μg erythromycin/ml and 200 μg X-gal/ml, selleck chemical and grown for at 42°C. White colonies were picked and screened for the double-crossover event, initially by PCR, and then by DNA sequencing, which was carried out by the Microbiology Core Facility at Harvard Medical School (Boston, MA). The mutation was transduced to strain 10833 using phage 80α [26] to produce strains 10833ΔisaB::erm and SA113ΔisaB::erm. Cellular localization of

IsaB Sa113 and Sa113ΔisaB::erm were grown in 1 L TSB for 6–10 hours. Cultures were centrifuged and both the cell pellet and spent medium were collected. Protein from 400 ml spent medium was precipitated by 70% saturation (NH4)2SO4, while stirring at 4°C for 1 hour. Precipitated proteins were collected

by centrifugation, the resulting pellet was resuspended in 1 ml of PBS with complete protease inhibitor cocktail tablets (Roche Diagnostics). The samples were dialyzed against 3 L of 0.1× PBS overnight at 4°C before gel electrophoresis. The cell pellet was washed with PBS and resuspended in 20 ml of Buffer A (40 mM Tris-Cl, 100 mM NaCl, 27% Sucrose, 20 mM MgCl2, and protease inhibitor cocktail 1/50 ml). 500 μg lysostaphin was added and the cells were incubated for 4 hours at 37°C. The pellet (protoplasts) and supernatant (peptidoglycan) were separated by centrifugation. The cell pellet was resuspended in 10 ml of water, 1% triton X was added and mixture was rocked for 10 min at RT. Samples were centrifuged 10,000 × g for 20 min to Selleck GSK872 remove intact cells and membranes were collected by centrifugation at 100,000 × g LY2874455 datasheet for 1 hr. Following centrifugation the supernatant (cytoplasm) was collected and the pellet (membrane) was resuspended in water. Equal amounts of protein

from the four cellular fractions were analyzed by denaturing PAGE using NuPAGE® 4–12% Bis-Tris gels (Invitrogen) according to manufacturer’s instructions. The proteins were transferred onto a PVDF membrane which was then blocked 1 hr in PBS containing 5% skim milk. The blot was probed with a 1:5,000 dilution of IsaB-specific rabbit antisera in PBS containing next 0.05% tween (PBST) and 0.5% skim milk followed by a 1:10,000 fold dilution of goat anti-rabbit horseradish peroxidase conjugated IgG in PBST. Proteins were detected using the ECL Plus detection system (Amersham) and analyzed with a CCD camera (Kodak). Electrophoretic mobility shift analysis Probes for EMSAs were fluorescently labeled with the ULYSIS™ Alexa Fluor® 594 Nucleic Acid labeling kit (Invitrogen) according to manufacturer’s instructions. Mobility shift reaction mixtures containing 20 μL binding buffer (BB1: 20 mM HEPES, 1 mM DTT, 20 mM KCl, 200 μg BSA/ml, 10% glycerol), 480 pmol purified, recombinant IsaB (optimal concentration determined from Figure 3A, which had either 3.84 nmol, 1.