The complex whiJ locus mediates environmentally sensitive repression of development of Streptomyces coelicolor A3(2).
A segment of DNA was isolated that complemented several poorly characterised sporulation-defective white-colony mutants of Streptomyces coelicolor A3(2) from an early collection (Hopwood et al., J Gen Microbiol 61: 397-408, 1970). Complementation was attributable to a gene, SCO4543, named whiJ, encoding a likely DNA-binding protein. Surprisingly, although some mutations in whiJ had a white colony phenotype, complete deletion of the wild-type or mutant gene gave a wild-type morphology. The whiJ gene is a member of a large paralogous set of S. coelicolor genes including abaAorfA, which regulates antibiotic production; and genes flanking whiJ are paralogues of other gene classes that are often associated with whiJ-like genes (Gehring et al., Proc Natl Acad Sci USA 97: 9642-9647, 2000). Thus, the small gene SCO4542 encodes a paralogue of the abaAorfD gene product, and SCO4544 encodes a paralogue of a family of likely anti-sigma factors (including the product of abaAorfB). Deletion of SCO4542 resulted in a medium-dependent bald- or white-colony phenotype, which could be completely suppressed by the simultaneous deletion of whiJ. A model is proposed in which WhiJ binds to operator sequences to repress developmental genes, with repression being released by interaction with the WhiJ-associated SCO4542 protein. It is suggested that this activity of SCO4542 protein is prevented by an unknown signal.
Aínsa
José A
JA
Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK.
Bird
Nick
N
Ryding
N Jamie
NJ
Findlay
Kim C
KC
Chater
Keith F
KF
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D009875:Operator Regions, Genetic; D011485:Protein Binding; D048372:Streptomyces coelicolor / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins