Repression of antibiotic downregulator WblA by AdpA in Streptomyces coelicolor

Abstract

The upstream region of antibiotic downregulatory wblA in Streptomyces coelicolor was found to contain AdpA binding motifs. A key morphological regulator, AdpA was shown to specifically bind these motifs by electrophoretic mobility shift assay. An adpA disruption mutant exhibited increased wblA transcription, suggesting that AdpA negatively regulates wblA transcription in S. coelicolor.

Fig 1

Putative AdpA binding motifs (A) and intergenic sequences (SCO3579 and SCO3580) in the wblA gene region of the S. coelicolor chromosome (B). Bent arrows, putative promoter designations (P1, P2, and *P3) presented in reference ; *P3, major transcription start point; underlined sequences, close matches to the consensus sequence for promoters recognized by σ^F in M. tuberculosis (34); boxes, putative AdpA binding motifs (gray box, contains 2 to 3 mismatches; black box, contains a perfect match). (C) Alignment of AdpA binding consensus sequences in the upstream region of wblA represented with positions and directions.

Fig 2

EMSA results. Increasing amounts of AdpA_SC protein were incubated with various regions of the wblA upstream fragment. PCR-amplified adpA_SC promoter was used as a positive control, and PCR-amplified intergenic sequence without a binding motif was used as a negative control.

Fig 3

Transcriptional analysis of target genes from S. coelicolor M145, the S. coelicolor ΔadpA_SC mutant, and the S. coelicolor ΔwblA mutant at different time points (8, 25, and 35 h). All cultures were performed in triplicate, and the averages are shown. The y axis scale represents the expression value relative to that of hrdB, a housekeeping sigma factor (which was set to 1).