Dual Transcriptional Control of amfTSBA, Which Regulates the Onset of Cellular Differentiation in Streptomyces griseus

AUTOR(ES)

Ueda, Kenji

FONTE

American Society for Microbiology

RESUMO

The amf gene cluster encodes a probable secretion system for a peptidic morphogen, AmfS, which induces aerial mycelium formation in Streptomyces griseus. Here we examined the transcriptional control mechanism for the promoter preceding amfT (PamfT) directing the transcription of the amfTSBA operon. High-resolution S1 analysis mapped a transcriptional start point at 31 nucleotides upstream of the translational start codon of amfT. Low-resolution analysis showed that PamfT is developmentally regulated in the wild type and completely abolished in an amfR mutant. The −35 region of PamfT contained the consensus sequence for the binding of BldD, a pleiotropic negative regulator for morphological and physiological development in Streptomyces coelicolor A3(2). The cloned bldD locus of S. griseus showed high sequence similarity to the S. coelicolor counterpart. Transcription of bldD occurred constitutively in both the wild type and an A-factor-deficient mutant of S. griseus, which suggests that the regulatory role of BldD is independent of A-factor. The gel retardation assay revealed that purified BldD and AmfR recombinant proteins specifically bind PamfT. Overproduction of BldD in the wild-type cell conferred a bald phenotype (defective in aerial growth and streptomycin production) and caused marked repression of PamfT activity. An amfT-depleted mutant also showed a bald phenotype but PamfT activity was not affected. Both the bldD-overproducing wild-type strain and the amfT mutant were unable to induce aerial growth of an amfS mutant in a cross-feeding assay, which indicates that these strains are defective in the production of an active AmfS peptide. The results overall suggests that two independent regulators, AmfR and BldD, control PamfT activity via direct binding to determine the transcriptional level of the amf operon responsible for the production and secretion of AmfS peptide, which induces the erection of aerial hyphae in S. griseus.

Documentos Relacionados

• AmfS, an Extracellular Peptidic Morphogen in Streptomyces griseus
• Characterization of an A-Factor-Responsive Repressor for amfR Essential for Onset of Aerial Mycelium Formation in Streptomyces griseus
• Transcriptional Control by A-Factor of Two Trypsin Genes in Streptomyces griseus
• Molecular cloning and characterization of the obg gene of Streptomyces griseus in relation to the onset of morphological differentiation.
• Transcriptional Switch On of ssgA by A-Factor, Which Is Essential for Spore Septum Formation in Streptomyces griseus