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Biomedical subjects

M Feiss

Publications and source records attributed to M Feiss.

67 records · Page 4Linked to original sources
PubMed1979

Identification of the C. coli dnaK (groPC756) gene product.

The E. coli dnaK (groPC756) gene product is essential for bacteriophage lambda DNA replication. Bacterial DNA segments carrying this gene have been cloned onto a bacteriophage lambda vector. The product of the dnaK gene has been identified on SDS polyacrylamide gels after infection of UV-irradiated E. coli cells. The dnaK gene codes for a polypeptide with an apparent molecular weight of 93,000-Mr. Transducing phages carrying amber mutations in the dnaK gene fail to induce the synthesis of the 93,000-Mr polypeptide chain upon infection of sup+ bacteria, but do so upon infection of supF bacteria. E coli carrying the dnaK756 mutation are, in addition, temperature sensitive for growth at 43 degrees C. It is shown that the dnaK756 mutation results in an overproduction of the dnaK gene product at that temperature.

Bacterial Proteins↗
PubMed1979

Expression of the yeast galactokinase gene in Escherichia coli.

In Saccharomyces cerevisiae the genes for three of the enzymes involved in galactose metabolism are tightly linked near the centromere of chromosome II (Douglas and Hawthorne, 1964). However, the molecular mechanisms which control the expression of these genes are not well understood. A DNA fragment containing at least one of these yeast genes, the galactokinase gene (gal1), has been joined to the bacterial plasmid pBR322 and maintained in an Escherichia coli strain that carries a deletion in its own galactokinase gene, galK. The presence of the yeast gene was demonstrated by (i) complementation of the E. coli galactokinase deletion, (ii) by hybridization of the cloned DNA fragment to restriction enzyme digests of total yeast DNA and (iii) by assaying for yeast galactokinase activity in bacterial cell extracts. The yeast DNA fragment is 4700 base pairs long, and enables the host E. coli K-12 strain to grow in minimal medium containing galactose as the sole carbon source with a generation time of 14.3 h. The yeast galactokinase activity in the bacterial extracts is 0.7% of the bacterial galactokinase activity found in wild-type E. coli fully induced with fucose.

DNA↗
PubMed1978

Genetic analysis of two genes, dnaJ and dnaK, necessary for Escherichia coli and bacteriophage lambda DNA replication.

We show that a collection of 93 E. coli mutations which map between thr and leu and which block phage lambda DNA replication define two closely linked cistrons. Work published in the accompanying paper shows that these mutations also affect host DNA replication, so we designate them dnaJ and dnaK; the gene order is thr--dnaK--dnaJ--leu. Demonstration of two cistrons was possible with the isolation of lambda transducing phages carrying one or the other or both of the dna genes. These phages were employed in phage vs bacterial complementation studies which unambiguously show that dnaK and dnaJ are different cistrons.

Coliphages↗
PubMed1977

A new host gene (groPC) necessary for lambda DNA replication.

The isolation of a bacterial mutation in a gene, designated groPC, which affects the growth of phages lambda and P2 is described. Lambda replication is severely limited in the strain, and some lambda pi mutations, which map in (or near) the P gene, allow growth. The gro mutation, groPC259, is recessive to wild type and maps between threonine (thr) and diaminopimelate (dapB) on the E. coli chromosome. The possibility that the groPC gene is concerned with host DNA replication is discussed.

Chromosome Mapping↗
PubMed1972

Isolation of plaque-forming, galactose-transducing strains of phage lambda.

Plaque-forming, galactose-transducing lambda strains have been isolated from lysogens in which bacterial genes have been removed from between the galactose operon and the prophage by deletion mutation.-A second class has been isolated starting with a lysogenic strain which carries a deletion of the genes to the right of the galactose operon and part of the prophage. This strain was lysogenized with a second lambda phage to yield a lysogen from which galactose-transducing, plaque-forming phages were obtained. These plaque-forming phages were found to be genetically unstable, due to a duplication of part of the lambda chromosome. The genetic instability of these partial diploid strains is due to homologous genetic recombindation between the two identical copies of the phage DNA comprising the duplication. The galactose operon and the duplication of phage DNA carried by these strains is located between the phage lambda P and Q genes.

Centrifugation, Density Gradient↗