Molecular and cytological analysis of the expression ofStreptomycessporulation regulatory genewhiH

Abstract

The whiH gene is required for the orderly sporulation septation that divides aerial hyphae into spores in Streptomyces coelicolor. Here, we use a whiHp-mCherry transcriptional reporter construct to show that whiHp is active specifically in aerial hyphae, fluorescence being dependent on sporulation sigma factor WhiG. The results show that the promoter is active before the septation event that separates the subapical compartment from the tip compartment destined to become a spore chain. We conclude that WhiG-directed RNA polymerase activity, which is required for whiH transcription, must precede this septation event and is not restricted to apical sporogenic compartment of the aerial hyphae. Further, it is demonstrated that WhiH, a predicted member of the GntR family of transcription factors, is able to bind specifically to a sequence in its own promoter, strongly suggesting that it acts as an autoregulatory transcription factor. Finally, we show by site-directed mutagenesis and a genetic complementation test that whiH is translated from a start codon overlapping with the previously identified transcription start point, implying leaderless transcription.

Carbon Catabolite Regulation of Secondary Metabolite Formation and Morphological Differentiation in Streptomyces coelicolor

“…These are also involved in morphological differentiation. WhiH is required for orderly sporulation and septation, splitting aerial hyphae into spores and also works as an auto-repressive factor [42]. The sigma factor BldN activates expression of chaplins and rodlins (confirmed by our transcriptome) and expression of the BldM [43].…”

Taxonomy, Physiology, and Natural Products of Actinobacteria

“…Some of the best-studied examples are bldD, a highly pleiotropic transcription factor that controls hundreds of development-related genes (200)(201)(202), the RNA polymerase factors bldN (203) and whiG (204,205), which control early events during sporulation (although bldN is also strongly transcribed during aerial growth), and whiH, which controls the onset of sporulation-specific cell division (206,207). There is also extensive control at the translational level.…”

An overview on transcriptional regulators in Streptomyces

“…Streptomyces coelicolor whiH Needed for sporulation and septation [207] t4:1 transport [208]. The asparagine synthase C (AsnC), which is involved 458 in asparagine biosynthesis [58,137] [218].…”

“…Specific TFs ("low level" regulators) 202 regulate the expression of genes usually located in the same operon or 203 cluster, as is the case of RedD and ActIIORF4, which control the bio-204 synthesis of undecylprodigiosin (RED) and actinorhodin (ACT) in 205 S. coelicolor, respectively [12,160]. In contrast, global TFs ("higher 206 level" regulators) may exert their function over a larger set of genes 207 belonging to distinct clusters along the genome. Recently, 36 and 208 162 TF-binding sites for the GlnR and BldD regulators were found 209 in Streptomyces venezuelae [212] and S. coelicolor [57], respectively.…”