Identification of DNA-binding proteins involved in regulation of expression of theStreptomyces aureofaciens whiH gene encoding a sporulation transcription factor

• Published in: Folia microbiologica Vol. 46; no. 6; pp. 527 - 534
• Main Authors: Homerová, D., Kormanec, J.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.12.2001
• Subjects: Bacteria; Binding sites; Deoxyribonucleic acid; Developmental stages; Differentiation; DNA; DNA-binding protein; Electrophoretic mobility; Footprinting; Gene expression; Homology; Mycelia; Nucleotides; Proteins; Repressors; Spores; Sporulation; Substrates
• ISSN: 0015-5632; 1874-9356
• DOI: 10.1007/BF02817997

Using the gel mobility-shift assay with protein fractions from different developmental stages of solid-grownStreptomyces aureofaciens, we identified two different proteins specifically bound to thewhiH promoter region. Only one protein (RwhA) was detected in young substrate mycelium cultivated in liquid medium. On comparing the mobility of the resulting complexes, one of the bound proteins present in substrate mycelium and in early stages of aerial mycelium seemed to be identical with the RwhA. The other detected protein with a higher mobility (RwhB) was present in all developmental stages except for mature spores. DNA footprinting analysis localized the binding site of RwhB to nucleotides −23 to +40 relative to the transcription start point of the PwhiH promoter. RwhA from young substrate mycelium protected the DNA fragment from −106 to −77 in coding strand and −126 to −82 in noncoding strand. WhiH has homology to a large family of metabolism-related repressors and seems to regulate negatively its own expression. These observations (and the results of transcription analysis of thewhiH gene obtained earlier) suggest that two different proteins influence the expression ofwhiH gene inS. aureofaciens. The putative repressor-like RwhA protein protects expression ofwhiH in substrate mycelium either in liquid medium or during differentiation. The other detected protein, RwhB, which binds to thewhiH promoter region during differentiation, may represent two forms of WhiH, one with a repressor role at the beginning of differentiation and second with the role of activator at the time of sporulation.