Three genes hrdB, hrdD and hrdT of Streptomyces griseus IMRU 3570, encoding sigma factor-like proteins, are differentially expressed under specific nutritional conditions

• Published in: Gene 1995-02, Vol.153 (1), p.41-48
• Main Authors: Marcos, Ana T., Gutiérrez, Santiago, Diez, Bruno, Fernández, Francisco J., Oguiza, JoséA., Martin, Juan F.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Bacterial Proteins - genetics; Base Sequence; Candicidin - metabolism; Culture Media - pharmacology; DNA-Directed RNA Polymerases - biosynthesis; DNA-Directed RNA Polymerases - chemistry; DNA-Directed RNA Polymerases - genetics; functional domain; Gene Expression Regulation, Bacterial; Genes, Bacterial; Hot Temperature; Molecular Sequence Data; Nucleic Acid Hybridization; Open Reading Frames; Phosphates - pharmacology; promoter; Protein Structure, Tertiary; RNA polymerase; rpoD box; Sequence Alignment; Sequence Homology, Amino Acid; Sigma Factor - biosynthesis; Sigma Factor - chemistry; Sigma Factor - genetics; Species Specificity; Streptomyces - genetics; Streptomyces aureofaciens; Streptomyces coelicolor; Streptomyces griseus; Streptomyces griseus - drug effects; Streptomyces griseus - genetics; Streptomyces griseus - metabolism; Transcription factors; Transcription, Genetic
• ISSN: 0378-1119; 1879-0038
• DOI: 10.1016/0378-1119(94)00759-L

Three genes ( hrd) homologous to the rpoD gene of Escherichia coli, that encode sigma factor-like proteins, have been cloned from DNA of the candicidin-producing strain Streptomyces griseus IMRU 3570. They are located in different regions of the chromosome. Sequence analysis showed that the first one is analogous to the hrdB gene of S. coelicolor. The second showed high similarity to the hrdD gene of S. coelicolor and S. aureofaciens and is linked, as in S. coelicolor, to a N-acetyltransferase-encoding gene ( nat) distantly related to the pat and bar genes that encode resistance to bialafos. The third showed no close homology with other known hrd genes from actinomycetes and has been named hrdT. Functional domains in the three S. griseus Hrd proteins are highly conserved in relation to those of the σ 70 protein family. Northern analysis showed that hrdB is expressed as a 1.9-kb transcript during active growth in phosphate-rich medium, but it is less efficiently transcribed under sporulation conditions (phosphate-starved) or after a heat-shock treatment. Two other shorter transcripts of 1.2 and 0.7 kb were also detected with the same probe. The hrdD gene is transcribed as a single 1.1-kb transcript under sporulation conditions following nutritional shiftdown and, to a lower extent, during growth conditions in phosphate-rich medium. The hrdT gene is weakly transcribed (1.5-kb RNA) under all conditions tested. The hrd-encoded sigma factors probably recognize actinomycetes promoters ( SEP type) with E. coli-like consensus sequences.