The dnaK operon of Streptomyces coelicolor encodes a novel heat-shock protein which binds to the promoter region of the operon.
Transcriptional studies have demonstrated that the dnaK gene of Streptomyces coelicolor A3(2) is contained within a 4.3 kb operon. The operon is transcribed from a single (transiently) heat-inducible promoter, dnaKp, that resembles the typical vegetative (sigma 70-recognized) eubacterial consensus promoter sequence. dnaK transcription was found to be heat-inducible at all stages of development in surface-grown cultures. In addition, at the normal growth temperature of 30 degrees C, dnaK transcript levels were shown to vary at different stages of development, being more abundant in young germinating cultures and in mycelium undergoing sporogenesis. The nucleotide sequence of the dnaK operon has been completed, revealing the gene organization 5'dnaK-grpE-dnaJ orfX. orfX represents a novel heat-shock gene. Its predicted product displays high similarity to the GlnR repressor proteins of Bacillus spp. and to the MerR family of eubacterial transcriptional regulators. The S. coelicolor OrfX protein has been over-produced in Escherichia coli, and DNA-binding experiments indicate that it interacts specifically with the dnaKp region, binding to three partially related inverted repeat sequences; they are centered at -75, -49 and +4, respectively, relative to the transcription start site of the operon. These results suggest that OrfX plays a direct role in the regulation of the dnaK operon.
Bucca
G
G
Department of Biochemistry and Applied Molecular Biology, UMIST, Manchester, UK.
Ferina
G
G
Puglia
A M
AM
Smith
C P
CP
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D002454:Cell Differentiation / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D018869:Heat-Shock Response; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009876:Operon / Q000235:genetics; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013302:Streptomyces / Q000235:genetics* / Q000254:growth & development; D014158:Transcription, Genetic
D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D011994:Recombinant Proteins; C063842:dnaK protein, E coli