Role of Rex in gene expression.

A. Promoter region of Rex controlled genes. Putative Rex binding sites are underlined. −35 and−10 promoter elements are highlighted in grey. Transcription start sites identified by RNA sequencing are indicated by large italic letters. B. Activities of the purC, adhE, adhP, gbs0609, rex, menA, gbs1388, gbs0110 and cdnP promoter-lacZ fusions. Cells were grown in M17 medium supplemented with 0.2% glucose. β-galactosidase activities were determined in log-phase growing cells. Ratios of the activities from the Δrex mutant to those of the WT are shown. Experiments were performed three times. Mean values and standard deviations are shown. LacZ activities in the WT strains were: purC, ~1 M. U.; adhE, ~8 M. U.; adhP ~1 M.U. gbs0609, ~2 M. U.; rex ~1.5 M. U.; menA, ~10 M. U.; gbs1388 ~200 M.U. gbs0110 ~70 M.U. cdnP ~ 30 M. U. For gbs1529, no induction was observed (R = 1). PmenA, gbs1388 and gbs0110 where P (EPS)