capsulatus SB1003

were carried out as previously described [6]. The resulting kanamycin and kanamycin/spectinomycin resistant strains (Additional file 1) were confirmed to contain the gene disruptions by PCR using the original amplification primers (Additional file 3) whereby replacement of the wild type gene by the disrupted version was indicated by amplification of a single product of the expected size. In trans complementation was performed using wild type genes with their native upstream sequences placed on the low copy, broad host range plasmid, pRK767 [49]. A wild type fragment of rbaV and rbaW was amplified using primers VcF and VW-R. Primers VcF and Anti-anti-R were used to amplify the wild type rbaV fragment. The rbaW selleck chemicals complement sequence contained an in-frame deletion of the majority of rbaV, replacing bp 24 to bp 272 with a KpnI site. This was created by joining 2 fragments, amplified with VcF and VdR, and VdF and VW-R, via a primer-embedded KpnI site. The

complementation vectors (Additional file 2) were conjugated into R. capsulatus using E. coli S17-1 [50]. Gene transfer bioassays Gene transfer bioassays were used as previously described [6] to measure production and release of RcGTA particles. Stationary phase cultures were filtered using 0.45-μm PVDF syringe filters and filtrates assayed for RcGTA activity using the R. capsulatus puhA strain, DW5 [51], as check details the recipient cells. The samples were plated on YPS agar and incubated in anaerobic phototrophic conditions and colony numbers were counted after 48 hours. RcGTA activities in mutant strains were determined as ratios relative to SB1003 in 3 replicate experiments. Statistically significant differences in RcGTA activities were identified by one-way analysis of variance (ANOVA) in R [52]. Western blotting Western blots targeting the ~32 kDa RcGTA major capsid protein were performed on the same cultures used for RcGTA activity assays

as described previously [6]. Samples contained 5 μl of cells pelleted from cultures and re-suspended in an equal volume of TE buffer or 10 μl of the culture supernatants mixed with 3× SDS-PAGE sample buffer and heated for 5 minutes at 98°C. The proteins were Tolmetin separated on a 10% SDS-PAGE gel and transferred to a nitrocellulose membrane by electro-blotting in transfer buffer [48 mM Tris Base, 39 mM glycine, 20% methanol (v/v)]. Total protein levels within buy LB-100 supernatant and cell sample groups were verified to be approximately equivalent by staining the membranes with Ponceau-S. The membranes were rinsed and blocked with a 5% (w/v) skim milk solution in TBST [20 mM Tris, 137 mM NaCl, 0.1% Tween-20 (v/v); pH 7.5] and incubated overnight at 4°C with an anti-Rhodobacterales GTA major capsid protein primary antibody (Agrisera, Vännäs, Sweden) [53] as a 1:1000 dilution in TBST.