FIG 3 .

Arabinan promotes transcription of arabinan PUL genes and arabinose utilization genes in a BT0366-dependent manner. (A) mRNA levels of the BT0364, BT0367, and BT0366 genes in isogenic BT0366 (GT44) and wild-type (WT, GT23) B. thetaiotaomicron prior to the switch (−5) and after 1 and 2 h of exposure to minimal medium containing 0.1% arabinan. (B) Western blot of crude extracts from a strain specifying an HA-tagged BT0366 protein (NS204) collected from cultures grown to mid-log phase in minimal medium containing 0.5% glucose (−5) or 30, 60, and 120 min after switching to medium containing 0.1% arabinan. Data are representative of three independent experiments, which produced similar results. (C) mRNA levels of the araM gene in isogenic BT0366 mutant (GT44) and wild-type (GT23) B. thetaiotaomicron prior to the switch (−5) and after 1 and 2 h of exposure to minimal medium containing 0.1% arabinan. Graphed are the mean and standard error of the mean from at least three independent experiments. Asterisks indicate significant differences from the wild-type strain for BT0364 and BT0367 expression and significant difference from the −5 sample for BT0366 expression (*, P ≤ 0.05; **, P ≤ 0.01 by two-tailed Student’s t test). Note log scale of y axis in panels A and C.