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At least 37 records · Page 2Linked to original sources
PubMed1977

Ficellomycin and feldamycin; inhibitors of bacterial semiconservative DNA replication.

The two peptide-like antibiotics ficellomycin and feldamycin impair semiconservative DNA replication but not DNA repair synthesis in bacteria. Specifically both antibiotics cause the accumulation of a 34S DNA species in toluenized Escherichia coli cells which lacks the capability of being integrated into larger DNA pieces and eventually the complete bacterial chromosome. Novobiocin, a known inhibitor of replicative DNA synthesis, was investigated for comparative purposes. The action of this latter antibiotic differs from the ones exerted by ficellomycin and feldamycin in the novobiocin appears to block an event associated with the initiation of Okazaki fragments. The fact that novobiocin impairs DNA gyrase suggests that this enzyme plays an essential role during the initiation of Okazaki pieces.

Anti-Bacterial Agents↗
PubMed1979

Bacterial DNA synthesized under phage control in a DNA-defective Salmonella-mutant and packaged into a special fraction of transducing particles of phage P22.

Lysates of P22 contain a small fraction of transducing particles with bacterial DNA replicated semiconservatively after the time of infection. It was demonstrated that the presence and relative amount of this class of transducing particles was unchanged, if infection of Salmonella occured under a condition nonpermissive for bacterial DNA replication. Analysis of particles with DNA fragments derived from different regions of the Salmonella chromosome indicated that the replication of the bacterial DNA carried by these transducing particles was not initiated specifically at the normal origin for bacterial chromosome replication.

DNA Replication↗
PubMed2005

Interplay between DNA replication and recombination in prokaryotes.

The processes of DNA replication and recombination are intertwined at many different levels. In diverse systems, extensive DNA replication can be triggered by genetic recombination, with assembly of a replication complex onto a D-loop recombination intermediate. This and related pathways of replisome assembly allow the completion of DNA replication when forks initiated at a conventional replication origin fail before completing replication of the genome. In addition, the repair of double-strand breaks or gaps by homologous recombination requires at least limited DNA replication to replace the missing information. An intricate interplay between replication and recombination is also evident during the termination of bacterial DNA replication and during the induction of the bacterial SOS response to DNA damage.

Bacteriophage T4↗
PubMed1999

Termination of DNA replication of bacterial and plasmid chromosomes.

Sequence-specific replication termini occur in many bacterial and plasmid chromosomes and consist of two components: a cis-acting ter site and a trans-acting replication terminator protein. The interaction of a terminator protein with the ter site creates a protein-DNA complex that arrests replication forks in a polar fashion by antagonizing the action of the replicative helicase (thereby exhibiting a contrahelicase activity). Terminator proteins also arrest RNA polymerases in a polar fashion. Passage of an RNA transcript through a terminus from the non-blocking direction abrogates replication termination function, a mechanism that is likely to be used in conditional termini or replication check points.

Bacillus subtilis↗
PubMed1981

The influence of host DNA replication on the formation of infectious and transducing Mu-particles.

We have investigated the influence of bacterial DNA replication on the formation of infectious and transducing Mu-particles. The data obtained agree with the previous findings that growth of phage Mu is independent of the host dnaA gene product (Toussaint and Faelen 1974), but required bacterial replication forks (Fitts and Taylor 1980). The replication of transducing DNA during phage development (Teifel and Schmieger 1979) is controlled by the host and is not a precondition for its packaging. Packaging of transducing DNA does not require a a nearby Mu genome.

Bacteriophage mu↗
PubMed1975

Accumulation of replicating bacterial plasmid DNA during thymine limitation or hydroxyurea treatment.

The rate of DNA chain elongation of a thymine auxotroph of Proteus mirabilis harboring an R factor was reduced by either thymine limitation or treatment with hydroxyurea. Using CsCl density gradient centrifugation, sedimentation in sucrose gradients, and electron microscopy, it has been shown that the fraction of total R factor DNA which is in the process of replication is greatly increased when the rate of DNA chain elongation is reduced while the initiation of plasmid replication continues at the normal rate. This makes possible the isolation and characterization of replicating plasmid DNA. Electron microscopy revealed that replicating R factor DNA consists of double-branched (theta type) circular molecules.

Centrifugation, Density Gradient↗
PubMed1992

DNA replication, the bacterial cell cycle, and cell growth.

The coupling of replication to the cell cycle and cell growth involves events that occur at oriC. Immediately after initiation, there is an eclipse phase during which reinitiation from the newly synthesized origins is prevented. GATC sites in oriC remain in a hemimethylated state longer than other sites because of their association with the outer membrane, which prevents DnaA from binding and activating additional rounds of initiation. After the origins are methylated and released from the outer membrane, the concentration of newly synthesized DnaA and the activation of oriC by transcription from the nearby mioC and gid promoters determine when the next rounds of replication initiate. If growth rate is reduced, the synthesis of (p)ppGpp will increase, and this will lead to a decrease in dnaA, mioC, and gid transcription. On the other hand, if growth rate is increased by access to a tasty meal, synthesis of (p)ppGpp will decrease, expression of dnaA, mioC, and gid genes will increase, and a shortening of the interinitiation time will result. The participation of all these control features ensures rapid and precise coordination of DNA replication with cell growth.

Bacteria↗
PubMed1972

The characteristics and genetic map location of a temperature sensitive DNA mutant of E. coli K12.

A temperature sensitive strain of E. coli K12 has been isolated in which residual DNA synthesis occurs at the 40 degrees C restrictive temperature; syntheses of RNA, protein and DNA precursors are not directly affected. The mutation has been designated dna-325 and is located at 89 min on the E. coli map in the same region where the dnaC locus is found. dnaC mutants are considered to be defective in DNA initiation. Some of the data are consistent with the view that the dna-325 mutation is temperature sensitive in the process of DNA initiation rather than DNA chain elongation: (1) more than two cell divisions occur after a shift to 40 degrees C; (2) upon a shift down to 30 degrees C, cell division occurs again only after the DNA content of the cells has doubled; (3) 80% more DNA is made at 30 degrees C in the presence of chloramphenicol after prior inhibition of DNA synthesis at 40 degrees C. These three observations indicate that rounds of DNA replication were completed at 40 degrees C. Also (4) infective lambda particles can be made at 40 degrees C long after bacterial DNA replication has ceased. It appears however that some DNA initiation can occur at 40 degrees C since (1) a limited amount of DNA synthesis does occur at 40 degrees C after prior alignment of the chromosomes by amino acid starvation at 30 degrees C, and (2) after incubation in bromouracil at the restrictive temperature, heavy DNA is found with both strands containing bromouracil.

Amino Acids↗
PubMed1984

Conjugative transfer of IncI1 plasmid DNA primase.

DNA primase of ColIb-P9drd-1 generates RNA primers that are thought to initiate DNA synthesis on the conjugatively transferred strand of the plasmid. To examine whether plasmid-specified primase is transferred during conjugation, we exploited the property of the enzyme to promote bacterial DNA replication in dnaG (primase-defective) mutants of Escherichia coli. It was found that dnaG3 recipient cells, treated with rifampicin to inhibit transcription, recovered ability to synthesise bacterial DNA by a process requiring an active plasmid primase gene in donor cells and a functional conjugation system. A non-transferable primase gene in the donor strain complemented a primase-negative derivative of ColIb-P9drd-1, confirming that the enzyme responsible for recovery was supplied by donor cells. The implication is that certain proteins are transmitted from donor cells to promote conjugative metabolism of plasmid DNA in the recipients.

Chromosomes, Bacterial↗
PubMed1991

Pseudomonad replication origins: a paradigm for bacterial origins?

Structural features of three analysed bacterial DNA replication origin classes (six enteric origins, three pseudomonad origins, and the Bacillus subtilis origin region) are compared in order to deduce characteristics common to all bacterial origins and characteristics that distinguish the three origin classes. The two Pseudomonas aeruginosa origins are shown to map within 10 kb of each other, and correlations are drawn with four potential origin regions in B. subtilis. The enteric origin class is further distinguished from the other two classes by its genetic organization, the presence of GATC sites, and the role of Dam methylation in enteric initiation. The pseudomonad origin class has the most features that are common to all of these bacterial origins, and hence may be the paradigm bacterial origin class.

Amino Acid Sequence↗
PubMed1977

A new bacterial gene (groPC) which affects lambda DNA replication.

A bacterial mutation affecting lambda DNA replication, called groPC756, has been mapped between the thr and leu bacterial loci. Most of the parental lambda DNA does not undergo even one round of replication in this host. Lambda mutants, call pi, which map in the lambda P gene are able to overcome the inhibitory effect of the groPC756 mutation. It is shown that the mutation at the groPC locus also interferes with bacterial growth at 42 degree C. A lambda-transducing phage,carrying the groPC+ allele, was isolated as a plaque-former on groPC756 bacteria. Upon lysogenization, it restores both the gro+ and temperature resistant phenotypes.

Chromosome Mapping↗