Disease relevance of SCO5621

• The positions of the sigma-factor genes, whiG and sigF, in the hierarchy controlling the development of spore chains in the aerial hyphae of Streptomyces coelicolor A3(2) [1].
• Here, we show that the whiG gene product, purified from an Escherichia coli strain carrying an expression construct, could activate E. coli core RNA polymerase in vitro to transcribe a sigma D-dependent motility-related promoter from B. subtilis [2].
• A library of S. coelicolor DNA was prepared in a phi C31 temperate phage vector (KC516), and one recombinant phage (KC750) that could restore the wild-type phenotype to a collection of whiG mutants when integrated into their genomes was found [3].
• In a survey of DNA from diverse actinomycetes by Southern blotting, all samples tested hybridized with whiB, but only those representing genera capable of producing sporulating aerial mycelium hybridized with whiG [4].

High impact information on SCO5621

• In each case, target gene expression was upregulated during early colony development in the bldD background, suggesting that, in the wild type, BldD acts to repress premature expression of whiG, bldN and bdtA during vegetative growth [5].
• Construction of a strain carrying both the J1668 deletion and a whiG mutation demonstrated that the Esp phenotype depends on at least one of the genes required for the differentiation of aerial hyphae into spores [6].
• In the non-motile mycelial organism Streptomyces coelicolor A3(2), the sporulation gene whiG encodes a protein that closely resembles RNA polymerase sigma factors such as sigma D of Bacillus subtilis, which mainly control motility and chemotaxis genes [2].
• Thus, in unknown circumstances, the whiG-dependent ORFs may be expressed from a more remote promoter as part of a complex transcription unit [7].
• Both inserts caused expression of the adjacent xylE reporter gene present in the vector in a developmentally normal strain of S. coelicolor, but there was no xylE expression in an otherwise isogenic whiG mutant [7].

Biological context of SCO5621

• Subcloning experiments with low- and high-copy-number Streptomyces plasmid vectors allowed partial localization of whiG in the cloned DNA and revealed that hypersporulation was associated with the presence of extra copies of whiG [3].
• Thus, whiB transcription is not severely dependent on any of these developmental genes, among which whiG is the determinant of a putative sigma factor specific for, and crucial to, sporulation [8].

Associations of SCO5621 with chemical compounds

• In the whiG mutants, deposits were found throughout the aerial mycelium and the adjacent region of the substrate mycelium, but the morphology of all the deposits, i.e. whether they were in the form of granules of branched glycogen or large blobs of unbranched glycan, depended solely on GlgBI [9].

References