Fig. 4. ʟ-arabinose metabolism is required to enhance T3SS expression.

a Transcriptional reporter assay of wild-type EHEC, ∆araC and ∆araC + pSUaraC transformed with pMK1lux-PLEE1 cultured in MEM-HEPES alone (grey) or supplemented with ʟ-arabinose (green). Data are depicted as luminescence units (LUX) divided by the optical density (OD₆₀₀) of the sample. All samples were taken at the same point in growth (hour 7). b pMK1lux-PLEE1 reporter assays performed in the EHEC, ∆araBAD, ∆araE and ∆araFGH backgrounds. c pMK1lux-PLEE1 reporter assays performed in the EHEC and ∆araC backgrounds. For complementation, ∆araC was transformed with either pSU-araBADE or pSU-araE. Statistical significance was determined using a two-tailed student’s t-test (significant P = 0.0014, 0.0001, 0.0003, 0.0023, 0.0417, 0.0007 and 0.0001 where indicated from left to right on a–c). Error bars represent the standard error of the mean (n = 3 biological replicates). *, **, ***, **** and ns indicate P < 0.05, P < 0.01, P < 0.001, P < 0.0001 or not significant respectively. Source data are provided in the Source Data file.