𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Genetic inactivation of topoisomerase I suppresses a defect in initiation of chromosome replication in Escherichia coli

✍ Scribed by Louarn, Jacqueline ;Bouché, Jean-Pierre ;Patte, Josette ;Louarn, Jean-Michel

Publisher
Springer
Year
1984
Tongue
English
Weight
589 KB
Volume
195
Category
Article
ISSN
0026-8925

No coin nor oath required. For personal study only.

✦ Synopsis

A strain of Escherichia coli K12 harboring simultaneously the temperature-sensitive dnaA46 mutation and a deletion of the trp-topA-cysB region plates with the same full efficiency at 30 degrees C and 42 degrees C. We have analyzed the possible involvement of the gene coding for topoisomerase I, topA, in this suppression phenomenon. The Ts phenotype was retrieved upon introduction of a plasmid-borne DNA fragment including an active topA gene into this strain, but not upon introduction of the same fragment harboring a topA::Tn1000 insertion. Replication seems to remain DnaA-dependent in the delta (topA) strain, however, since we have been unable to introduce a dnaA::Tn10 allele. We propose either that the dnaA46 gene product is overproduced and compensates for its thermal inactivation, or that initiation at oriC demands less DnaA protein in the absence of topoisomerase I.

📜 SIMILAR VOLUMES

Overproduction of DnaA protein stimulate
Overproduction of DnaA protein stimulates initiation of chromosome and minichromosome replication in Escherichia coli
✍ Atlung, Tove ;Løbner-Olesen, Anders ;Hansen, Flemming G. 📂 Article 📅 1987 🏛 Springer 🌐 English ⚖ 1015 KB

Increased synthesis of DnaA protein, obtained with plasmids carrying the dnaA gene controlled by the heat inducible lambda pL promoter, stimulated initiation of replication from oriC about threefold. The overinitiation was determined both as an increase in copy number of a minichromosome and as an i

Chloramphenicol releases a block in init
Chloramphenicol releases a block in initiation of chromosome replication in a dnaA strain of Escherichia coli K12
✍ Lycett, Grantley W. ;Orr, Elisha ;Pritchard, Robert H. 📂 Article 📅 1980 🏛 Springer 🌐 English ⚖ 726 KB

DNA-DNA hybridisation experiments show that chloramphenicol induces a burst of initiation from the oriC region of a dnaA46 mutant of Escherichia coli at 36.5 degrees C but not from the isogenic dnaA+ strain. Following this stimulation of initiation is in parallel with the induced stimulation of RNA

Requirement of DNA Gyrase for the initia
Requirement of DNA Gyrase for the initiation of chromosome replication in Escherichia coli K-12
✍ Filutowicz, Marcin 📂 Article 📅 1980 🏛 Springer 🌐 English ⚖ 881 KB

It has been found that strains carrying mutations in the dnaA gene are unusually sensitive to COU, NAL or NOV, which are known to inhibit DNA gyrase activities. The delay in the initiation of chromosome replication after COU treatment has been observed in cells with chromosomes synchronized by amino

Transcriptional control for initiation o
Transcriptional control for initiation of chromosomal replication in Escherichia coli: fluctuation of the level of origin transcription ensures timely initiation
✍ Masayuki Su’etsugu; Akiko Emoto; Kazuyuki Fujimitsu; Kenji Keyamura; Tsutomu Ka 📂 Article 📅 2003 🏛 John Wiley and Sons 🌐 English ⚖ 641 KB

## Abstract **Background:** During the cell cycle, the initiation of chromosomal replication is strictly controlled. In __Escherichia coli__, the initiator DnaA and the replication origin __oriC__ are major targets for this regulation. Here, we assessed the role of transcription of the __mioC__ gen

RNase H-defective mutants of Escherichia
RNase H-defective mutants of Escherichia coli: A possible discriminatory role of RNase H in initiation of DNA replication
✍ Horiuchi, Takashi ;Maki, Hisaji ;Sekiguchi, Mutsuo 📂 Article 📅 1984 🏛 Springer 🌐 English ⚖ 632 KB

Mutants of Escherichia coli completely deficient in RNase H activity were isolated by inserting transposon Tn3 into the structural gene for RNase H, rnh, and its promoter. These rnh- mutants exhibited the following phenotypes; (1) the mutants grew fairly normally, (2) rnh- cells could be transformed