Disease relevance of pColKK235s01

• Here, we analyzed the effects of upstream sequences from several additional E. coli promoters (rrnD P1, rrnB P2, lambda pR, lac, merT, and RNA II) [1].

High impact information on pColKK235s01

• The ColE1 primer transcript (RNA II) hybridizes to the template DNA near the replication origin [2].
• In this paper, it is shown that binding of RNA I to the homologous RNA II is inhibited by an RNA I specified by a plasmid of different compatibility [3].
• Replication of ColE1-type plasmids is known to be regulated by a plasmid-specific RNA (RNA I), whose binding to the transcript (RNA II) from the primer promoter results in inhibition of formation of the primer for DNA replication [3].
• Subsequent digestion of the RNA in this RNA-pBR322 DNA hybrid results in the formation of a highly unwound DNA termed form I. If DNA gyrase is absent during the RNA polymerase-catalyzed elongation of RNA II, a stable RNA-pBR322 DNA hybrid can still form that is localized to the origin region of the genome [4].
• The first step, initial kissing complex formation, involves base pairing between complementary sequences in the hairpin loops of RNA I and RNA II [5].

Biological context of pColKK235s01

• RNA I prevents a transcript (RNA II) from the ColE1 primer promoter to form a hybrid with the template DNA and thereby inhibits formation of primer for DNA replication [6].
• We have constructed plasmids which do not possess the nucleotide sequence for RNA I, or the normal 5' terminus and promoter of RNA II [7].
• The promoter sequences for RNA II, but not those for RNA I, conformed to the -10 region consensus sequence for sigma 43 promoters [8].
• We found that the absence of Dam methylation abolishes the mutant phenotype and that under this condition the high mutant level of RNA II synthesis is reduced, which is accompanied by a restoration of the regulation by RNA I. The role of methylation in the regulation of plasmid replication is discussed [9].
• By abolishing sequence homology between ColE1 RNA I/RNA II and tRNAs, we were able to restore the plasmid's replication control mechanisms and to keep the plasmid copy number constant throughout the culture process, thereby prolonging metabolic activity and productivity of the bacterial expression system [10].

Associations of pColKK235s01 with chemical compounds

• RNA II was found in low amounts in exponentially growing cells but was not observed in stationary-phase cells, and the presence of RNA II was glucose insensitive [8].
• The RNA II analog, in these plasmids, is believed to be synthesized by the readthrough transcription of the upstream trimethoprim-resistant dihydrofolate reductase (DHFR) gene at a level comparable to that produced by the tryptophan promoter [7].
• ColE1 DNA replication is initiated by RNA II and inhibited by RNA I. Control of the replication occurs through the interaction between RNA I and RNA II [11].

Other interactions of pColKK235s01

• All of these elements (RNA I, RNA II, and rom) reveal a high level of similarity to ColE1 homologs [12].

Analytical, diagnostic and therapeutic context of pColKK235s01

• The synthesis RNA II:RNA I ratio obtained in hybridization assays was 2.4 for E. coli IHF+ and 4.4 for E. coli IHF-. Densitometric analysis of RT-PCR products indicates that the relative levels of RNA I in E. coli IHF+ and IHF-, are equal, but the relative level of RNA II in E. coli IHF is about four times higher than in E. coli IHF+ [13].

References