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R Calendar

Publications and source records attributed to R Calendar.

At least 73 records · Page 4Linked to original sources
PubMed1980

Genetic analysis of bacteriophage P4 using P4-plasmid ColE1 hybrids.

A set of plasmids that contain fragments of the bacteriophage P4 genome has been constructed by deleting portions of a P4-ColE1 hybrid. A P4 genetic map has been established and related to the physical map by examining the ability of these plasmids to rescue various P4 mutations. The P4 virl mutation and P4 genes involved in DNA replication (alpha), activation of P2 helper genes (delta and epsilon), polarity suppression (psu) and head size determination (sid) have been mapped, as has the region responsible for synthesis of a nonessential P4 protein. One of the deleted plasmids contains only 5900 base pairs (52%) of P4 but will form plaques if additional DNA is added to increase its total size to near that of P4. This plasmid is also unique in that it will not form stable associations with P2 lysogens of E. coli which are recA+. P4 alpha mutants can be suppressed as a result of replication under control of the ColE1 part of the hybrid.

Chromosome Mapping↗
PubMed1979

Gene for the RNA polymerase sigma subunit mapped in Salmonella typhimurium and Escherichia coli by cloning and deletion.

The genes for the RNA polymerase sigma subunit (rpoD) and DNA primase (dnaG) of Salmonella typhimurium have been cloned into lambda vectors. Combined restriction, deletion and functional analysis of the cloned fragment allows us to map the genes precisely on the fragment, establishes the direction in which rpoD is transcribed, and reveals the existence of at least one new gene in the vicinity. A closely homologous, smaller fragment of Escherichia coli DNA, also cloned into lambda, contains rpoD and at least part of dnaG.

Bacteriophage lambda↗
PubMed1978

Temperature-sensitive Escherichia coli mutant producing a temperature-sensitive sigma subunit of DNA-dependent RNA polymerase.

A gene affecting the sigma subunit of DNA-dependent RNA polymerase is tightly linked to dnaG at 66 min on the Escherichia coli chromosome. In order to create an easily selectable marker in this region, we inserted transposon-10, which carries a gene determining resistance to tetracycline (tet) near 66 min, and the order tolC-dnaG-sigma-tet was determined. We used frequency of contransduction with tet as a criterion to screen a collection of spontaneous temperature-sensitive Escherichia coli mutants that might affect the sigma subunit. One such mutant was found to map at the sigma locus. The sigma subunit isolated from this mutant is unstable at 46 degrees C in vitro and has an altered electrophoretic mobility. The temperature sensitivity of RNA synthesis in this mutant indicates that most transcription in E. coli is sigma dependent.

Chromosome Mapping↗
PubMed1977

A gene from Escherichia coli affecting the sigma subunit of RNA polymerase.

The RNA polymerase sigma subunits of Escherichia coli K, E. coli C, and Salmonella typhimurium can be resolved by electrophoresis. Using this technique, we have analyzed Salmonella strains carrying F' plasmids from E. coli K in order to map the gene for the sigma factor. Partial diploid analyses show the location of the sigma gene at 62-66 min on the E. coli genetic map. This gene is cotransducible with toIC and dnaG, at 66 min.

Chromosome Mapping↗
PubMed1975

Escherichia coli deoxyribonucleic acid synthesis mutants: their effect upon bacteriophage P2 and satellite bacteriophage P4 deoxyribonucleic acid synthesis.

Escherichia coli C strains containing different deoxyribonucleic acid (DNA) synthesis mutations have been tested for their support of the DNA synthesis of bacteriophage P2 and its satellite phage P4. Bacteriophage P2 requires functional dnaB, dnaE, and dnaG E. coli gene products for DNA synthesis, whereas it does not require the products of the dnaA, dnaC, or dnaH genes. In contrast, the satellite virus P4 requires functional dnaE and dnaH gene products for DNA synthesis and does not need the products of the dnaA, dnaB, dnaC, and dnaG genes. Thus the P2 and P4 genomes are replicated differently, even though they are packaged in heads made of the same protein.

Coliphages↗
PubMed1975

Interaction of P2 bacteriophage with the dnaB gene of Escherichia coli.

The dnaB gene product of Escherischia coli is required for multiplication of temperate phage P2. At 37 C in dnaB-ts mutnats, P2 will not plaque and gives a very small burst of progeny. P2 mutants have been isolated which can grow well enough to plaque under these conditions. This type of phage mutant is cis dominant, and one such mutant (P2rlb1) has been mapped near the left end of the early gene B and to the right of the cox4 (excision) mutation. The rlb1 mutation does not lie at the replication origin, but may affect transcription in the early region, which includes the replication origin. It may also represent a site on the P2 DNA which interacts with the dnaB gene product.

Chromosome Mapping↗