The dnaKJ operon of Agrobacterium tumefaciens: transcriptional analysis and evidence for a new heat shock promoter.
The dnaKJ operon of Agrobacterium tumefaciens was cloned and sequenced and was found to be highly homologous to previously analyzed dnaKJ operons. Transcription of this operon in A. tumefaciens was stimulated by heat shock as well as by exposure to ethanol and hydrogen peroxide. There were two transcripts representing the dnaKJ operon: one containing the dnaK and dnaJ genes and the second containing only the dnaK gene. Primer extension analysis indicated that transcription started from the same site in heat-shocked cells and in untreated cells. The upstream regulatory region of the dnaKJ operon of A. tumefaciens does not contain the highly conserved inverted repeat sequence previously found in the groESL operon of this bacterium, as well as in many other groE and dnaK operons. Sequence analysis of the promoter region of several groESL and dnaK operons from alpha-purple proteobacteria indicates the existence of a putative promoter sequence different from the known consensus promoter sequences recognized by the Escherichia coli vegetative or heat shock sigma factor. This promoter may constitute the heat shock promoter of these alpha-purple proteobacteria.
Segal
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Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Israel.
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D016960:Agrobacterium tumefaciens / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D018835:Chaperonin 10 / Q000096:biosynthesis; D018834:Chaperonin 60 / Q000096:biosynthesis; D003001:Cloning, Molecular; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D006360:Heat-Shock Proteins / Q000235:genetics*; D018869:Heat-Shock Response / Q000235:genetics*; D008969:Molecular Sequence Data; D009876:Operon; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D014158:Transcription, Genetic
D018835:Chaperonin 10; D018834:Chaperonin 60; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D012333:RNA, Messenger; C063842:dnaK protein, E coli