DNA binding assays were performed at 20 °C in a total volume of 10 μL mixture containing 1–32 ng of purified ht-FerC (0.025–0.80 pmol dimer), a DIG-labeled probe (0.5 nM of FER-102 or FER-66 probe; or 1.0 nM of FER-50 or FER-48 probe), 1.0 μg

of poly[d(I-C)], 0.1 μg of poly-l-lysine, and a reaction buffer [20 mM HEPES, 10 mM (NH4)2SO4, 1 mM dithiothreitol, 0.2% (w/v) Tween 20, 30 mM KCl, and 1 mM EDTA, pH 7.6] for 20 min, following the same procedure described earlier (Kamimura et al., 2010). To test ZD1839 price the association of FerC with effector molecules, ht-FerC (5 ng, 0.13 pmol) was previously incubated with 100 μM of feruloyl-CoA or other hydroxycinnamoyl-CoAs at 20 °C for 10 min. A FER-102 probe (1.0 nM) was then added to the mixture and incubated for 10 min. Gel electrophoresis and the detection of signals were performed according to a previous description (Kamimura et al., 2010). The ferA coding sequence was amplified using Prime STAR GXL DNA polymerase (Takara Bio Inc.) and the primer pair of ferA-Nde-F and ferA-Bam-R (Table S3). This fragment was inserted into pET-16b to yield pE16FA. FerA with an N-terminal His tag (ht-FerA) was produced in E. coli BL21(DE3) and purified by His Spin

Trap column, and the purity of ht-FerA was examined by SDS-PAGE. To prepare feruloyl-CoA, p-coumaroyl-CoA, caffeoyl-CoA, and sinapoyl-CoA, 2 mM of corresponding hydroxycinnamates

were incubated with 20 μg of purified ht-FerA at 25 °C for 6 h in the presence of 2.5 mM CoA, 3 mM MgSO4, and 3 mM ATP. Degradation of each hydroxycinnamate was examined by high-performance MAPK inhibitor liquid chromatography (ACQUITY ultraperformance liquid chromatography system; Waters). The change in absorbance of each reaction mixture was monitored by a V-630 spectrophotometer (Jasco Corp.) at the wavelengths of 345, 333, 346, and 346 nm derived from feruloyl-CoA, p-coumaroyl-CoA, caffeoyl-CoA, and sinapoyl-CoA, respectively (Beuerle & Pichersky, 2002). The reaction mixtures were filtered by an Amicon ultra spin filter unit (3-kDa cutoff, Millipore), and then the filtrates were used as preparations either of 2 mM hydroxycinnamoyl-CoAs. Nucleotide sequence of the SYK-6 genome (Masai et al., 2012) revealed that SLG_25040 (ferC), which is located 87 bp upstream of ferB (Fig. 1b), showed 20–27% identity at amino acid level with ferR of P. fluorescens BF13 (Calisti et al., 2008), badR of Rhodopseudomonas palustris (Egland & Harwood, 1999), and mobR of Comamonas testosteroni KH122-3a (Hiromoto et al., 2006; Yoshida et al., 2007). These gene products involved in the catabolism of ferulate, benzoate, and 3-hydroxybenzoate, respectively, belong to the family of MarR-type transcriptional regulator; therefore, ferC appears to encode a MarR-type transcriptional regulator.