Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Alu156 promoter isolated from the Bacillus subtilis bacteriophage SP82 is dependent on curved DNA upstream of the -35 region for efficient function. Short DNA insertions of 6-29 base pairs were used to simultaneously change the linear placement and rotational orientation of this curved DNA relative to the -35 region. When these mutant promoters were analyzed in vivo using transcriptional fusions with a chloramphenicol acetyltransferase gene, changes in the rotational orientation of the curved DNA correlated with changes in promoter function. The most efficient mutant promoters contained insertions of 11 and 21 base pairs, and insertions of 15 and 25 base pairs resulted in the least efficient mutant promoters. The importance of the proper rotational alignment of the curved DNA to promoter activity was also observed in vitro at the level of transcription of RNA polymerase binding. Based on the electrophoretic mobilities of DNA fragments containing the various insertion mutant promoters, there was a second region of curved DNA downstream of the insertion point. The findings are consistent with the idea that the curved DNA deflects the helix back toward the promoter-bound RNA polymerase molecule to allow the enzyme to interact directly with upstream DNA. These interactions are proposed to structure the DNA for the formation of the open promoter complex.
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PMID:Rotational orientation of upstream curved DNA affects promoter function in Bacillus subtilis. 254 69

The effect of DNA upstream of the -35 region on promoter function was examined using two promoters isolated from the Bacillus subtilis bacteriophage SP82. The affinity of RNA polymerase for the two promoters in vitro differed significantly. For each promoter the nucleotide sequence of the upstream DNA was characterized by the presence of successive runs of adenines with a 10-11-base pair periodicity. DNA fragments with the polyadenine-containing upstream DNA displayed aberrant electrophoretic mobilities when analyzed on polyacrylamide gels indicative of curved DNA. A series of mutant promoters in which the upstream DNA was deleted or altered was constructed. The curved DNA upstream of the -35 region was required for efficient RNA polymerase binding. Decreased in vitro transcription observed when the upstream DNA was deleted could be partially restored if the template was negatively supercoiled. Measurements of chloramphenicol acetyltransferase specific activity from B. subtilis strains carrying transcriptional fusions indicate that the curved upstream DNA stimulated transcription from the promoter with the weaker affinity for RNA polymerase. The curved DNA reduced the in vivo activity of the promoter with the strong affinity for RNA polymerase. One function of the curved upstream DNA may be to provide RNA polymerase-promoter interactions that facilitate open complex formation.
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PMID:Effect of polyadenine-containing curved DNA on promoter utilization in Bacillus subtilis. 313 65