PubMed Health⌕ Search

Biomedical subjects

B Magasanik

Publications and source records attributed to B Magasanik.

At least 145 records · Page 8Linked to original sources
PubMed1971

Nature and self-regulated synthesis of the repressor of the hut operons in Salmonella typhimurium.

The enzymes mediating histidine utilization, coded by the hut genes, in Salmonella typhimurium are synthesized from two closely-linked operons. Results presented in this paper show that these operons are regulated by a single repressor protein. The hutC gene, coding for this repressor, is part of one of the operons. Since this same operon is sensitive to the repressor, the repressor apparently represses its own synthesis.

Acrylates↗
PubMed1970

Catabolite-insensitive revertants of lac promoter mutants.

The maximum rate of expression of the lac operon is severely reduced in lac promoter mutants. Revertants of these mutations which produce higher levels of enzyme were isolated. Some of these revertants had lost sensitivity to catabolite repression and transient repression. The mutations responsible for these losses took place at sites very close to the original promoter mutations. From these results we conclude that the promoter itself is the target site for both catabolite and transient repression of the lac operon.

Chromosome Mapping↗
PubMed1970

Physiological basis of transient repression of catabolic enzymes in Escherichia coli.

Transient repression of catabolic enzymes occurs in cells that encounter a new carbon compound in their growth medium, but only when the cells contain the enzyme catalyzing the transfer of phosphate from phosphoenolpyruvate to a small heat-stable protein (HPr), as well as a permease capable of transporting the new compound across the cell membrane. The newly added compound need not be metabolized. The degree and duration of the transient repression have no obvious relation to the intracellular level of the exogenously added compound. It is suggested that the actual passage of the compound through the cell membrane is responsible for the repression.

Alkaline Phosphatase↗
PubMed1970

Gene expression after transformation of Bacillus subtilis.

Sensitive assays of histidase activity were used to follow the production of this enzyme as directed by a gene newly introduced into cells of Bacillus subtilis by transformation. Histidase activity can be detected in histidase-negative recipient cells within 1 hr after the addition of deoxyribonucleic acid extracted from histidase-positive donors. Enzyme production continues for one to two additional hours and then ceases. Histidase production in the transformed cells is fully sensitive to catabolite repression. Catabolite repression is rapidly established after transformation of recipient cells that are resistant to this form of regulation.

Bacillus subtilis↗
PubMed1969

Catabolite repression gene of Escherichia coli.

A catabolite repression gene (cat) which alters the sensitivity of Escherichia coli to catabolite repression has been mapped by transduction and shown to be located between the pyrC and purB genes. When the cat-1 mutation was studied in a number of genetic backgrounds, the results showed that this mutation affects the synthesis of more than one catabolic enzyme but does not completely eliminate catabolic repression under all conditions. It is suggested that this mutation may cause a block in the accumulation of the catabolite effector. Our experiments show that this effector is not glucose-6-phosphate.

Bacterial Proteins↗
PubMed1969

Molecular basis of transient repression of beta-galactosidase in Escherichia coli.

The molecular basis of transient repression of beta-galactosidase by glucose was examined. This repression acted only at the level of transcription. Apparently, it was not mediated by the I-gene product. Analysis of single cells in a culture subjected to transient repression showed that essentially all cells initially experienced repression and later became gradually resistant to repression.

Bacterial Proteins↗