Biomaterial Database

Interrelated effects of DNA supercoiling, ppGpp, and low salt on melting within the Escherichia coli ribosomal RNA rrnB P1 promoter. 1992

K L Ohlsen, and J D Gralla

Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.

The formation of complexes containing high levels of DNA melting at the ribosomal RNA rrnB P1 promoter in vitro is shown to be facilitated by DNA supercoiling or low salt. The effector nucleotide ppGpp is ineffective under these conditions. The loss of supercoils or addition of salt increases the effectiveness of ppGpp in inhibiting formation of these complexes. In vivo plasmid DNA supercoiling is shown to decrease during starvation protocols that also increase levels of ppGpp. The results suggest that ppGpp regulation may be affected by the state of DNA supercoiling in vivo.

UI	MeSH Term	Description	Entries
D011401	Promoter Regions, Genetic	DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes.	rRNA Promoter,Early Promoters, Genetic,Late Promoters, Genetic,Middle Promoters, Genetic,Promoter Regions,Promoter, Genetic,Promotor Regions,Promotor, Genetic,Pseudopromoter, Genetic,Early Promoter, Genetic,Genetic Late Promoter,Genetic Middle Promoters,Genetic Promoter,Genetic Promoter Region,Genetic Promoter Regions,Genetic Promoters,Genetic Promotor,Genetic Promotors,Genetic Pseudopromoter,Genetic Pseudopromoters,Late Promoter, Genetic,Middle Promoter, Genetic,Promoter Region,Promoter Region, Genetic,Promoter, Genetic Early,Promoter, rRNA,Promoters, Genetic,Promoters, Genetic Middle,Promoters, rRNA,Promotor Region,Promotors, Genetic,Pseudopromoters, Genetic,Region, Genetic Promoter,Region, Promoter,Region, Promotor,Regions, Genetic Promoter,Regions, Promoter,Regions, Promotor,rRNA Promoters
D004269	DNA, Bacterial	Deoxyribonucleic acid that makes up the genetic material of bacteria.	Bacterial DNA
D004278	DNA, Superhelical	Circular duplex DNA isolated from viruses, bacteria and mitochondria in supercoiled or supertwisted form. This superhelical DNA is endowed with free energy. During transcription, the magnitude of RNA initiation is proportional to the DNA superhelicity.	DNA, Supercoiled,DNA, Supertwisted,Supercoiled DNA,Superhelical DNA,Supertwisted DNA
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D006159	Guanosine Tetraphosphate	Guanosine 5'-diphosphate 2'(3')-diphosphate. A guanine nucleotide containing four phosphate groups. Two phosphate groups are esterified to the sugar moiety in the 5' position and the other two in the 2' or 3' position. This nucleotide serves as a messenger to turn off the synthesis of ribosomal RNA when amino acids are not available for protein synthesis. Synonym: magic spot I.	Alarmone ppGpp,Bacterial Magic Spot ppGpp,Guanosine 5'-(trihydrogen diphosphate), mono(trihydrogen diphosphate) (ester),Guanosine 5'-diphosphate 2'(3')-diphosphate,ppGpp,Guanosine 3'-Diphosphate 5'-Diphosphate,Guanosine 5'-Diphosphate 3'-Diphosphate,3'-Diphosphate 5'-Diphosphate, Guanosine,5'-Diphosphate 3'-Diphosphate, Guanosine,Guanosine 3' Diphosphate 5' Diphosphate,Guanosine 5' Diphosphate 3' Diphosphate,Tetraphosphate, Guanosine,ppGpp, Alarmone
D012407	rRNA Operon	Genetic loci which direct transcription of ribosomal RNA in bacterial operons. They are designated rrnB, rrnC, rrnD, etc. according to the structural position of the transcription unit in the DNA sequence.	Operon, rRNA,rrnB Operon,Operon, rrnB,Operons, rRNA,Operons, rrnB,rRNA Operons,rrnB Operons
D012492	Salts	Substances produced from the reaction between acids and bases; compounds consisting of a metal (positive) and nonmetal (negative) radical. (Grant & Hackh's Chemical Dictionary, 5th ed)	Salt