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Biomedical subjects

M Pirsel

Publications and source records attributed to M Pirsel.

23 records · Page 2Linked to original sources
PubMed1978

Uv-inducible repair II: its role in various defective mutants of Escherichia coli K-12.

Involvement of UV-inducible protein(s) in repair of various E. coli K-12 cell strains has been investigated using a procedure of double UV irradiation and postincubation with chloramphenicol. From the course of dose survival curves the following conclusions concerning significance of a UV-inducible protein have been drawn: 1. It is a very important for wild type cells; in these cells its early occurrence is necessary to prevent killing. 2. It is involved in repair of excision-deficient cells; however, its action early after UV is less urgent. 3. It is not involved at all in repair of lex mutant cells; 4. It exhibits some effect on survival of recA as well as recB mutant cells. We conclude that the protein is involved in excision repair as well as in resumption of DNA replication.

Bacterial Proteins↗
PubMed1977

Correlation between survival, ability to rejoin DNA and stability of DNA after preirradiation inhibition of protein synthesis in a rec mutant of Escherichia coli K12.

A 90 min inhibition of protein synthesis induced by starvation for amino acids (AA-) or by treatment with chloramphenicol (CAP) prior to UV irradiation (2.5 Jm-2) increased the resistance of the strain Escherichia coli K12 SR19 to UV radiation more than ten-fold. Under these conditions, cultures in which protein synthesis was inhibited before the UV irradiation rejoin short regions of DNA synthesized after the irradiation to a normal-size molecule, whereas an exponentially growing culture does not rejoin DNA synthesized after UV irradiation to a molecule of a normal size. In the exponentially growing culture both the parental and the newly synthesized DNA are unstable after the irradiation. In cultures with inhibited protein synthesis only the parental DNA is somewhat unstable. In Escherichia coli K12 SR19 where protein synthesis was inhibited before the irradiation, a correlation between the survival of cells, the ability to rejoin short regions of DNA synthesized after UV irradiation and a higher stability of both parental and newly synthesized DNAs could be demonstrated.

Amino Acids↗
PubMed1977

Replication of DNA in UV-irradiated Escherichia coli in the absence of amino acids.

Since pyrimidine dimers are considered to be the cause of the synthesis of short DNA segments, normalization of DNA replication after UV irradiation should be in a temporal correlation with their removal. This correlation holds in exponentially growing excision-proficient Escherichia coli cells. However, when these cells are preincubated and postincubated without amino acids, synthesis of short segments continues although dimers are efficiently excised.

Amino Acids↗
PubMedDate not supplied

Expression of the Escherichia coli recA gene in the yeast Saccharomyces cerevisiae.

The isolation of the protein coding region of the recA gene from Escherichia coli by extensive Bal31 digestion is described. The structural recA gene was ligated into an extrachromosomally replicating yeast expression vector, downstream of the yeast alcohol-dehydrogenase gene promoter region, to produce pADHrecA plasmid. The pADHrecA plasmid was transformed into the wild-type and the repair deficient strains of Saccharomyces cerevisiae. The crude protein samples were extracted from the individual yeast transformants. A 38 kDa protein was present in all transformants containing the recA gene on plasmid. Thus the recA gene from E coli was successfully expressed in cells from a lower eukaryote.

Alcohol Dehydrogenase↗