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Biomedical subjects

K I Wolska

Publications and source records attributed to K I Wolska.

At least 19 recordsLinked to original sources
PubMed2004

Influence of Escherichia coli DnaK and DnaJ molecular chaperones on tryptophanase (TnaA) amount and GreA, GreB stability.

The amount of tryptophanase was estimated in Escherichia coli deltadnaJ and deltadnaKdnaJ mutants. Densitometric analysis of polyacrylamide gels demonstrated that the amount of tryptophanase was diminished in both mutants. DnaK and DnaJ molecular chaperones apparently influence the amount of tryptophanase, the expression of which is regulated at all transcription steps, including transcription elongation. The half-life of GreA and GreB proteins (being activators of transcription elongation of the tna operon) are diminished in both mutants suggesting the involvement of DnaK and DnaJ in the stability of these proteins.

Escherichia coli↗
PubMed2002

Effect of mutations in dnaK and dnaJ genes on cysteine operon expression in Escherichia coli.

The effect of mutations in dnaK and dnaJ genes on the expression of two operons that are part of cysteine regulon was determined using Escherichia coli strains harboring cysPTWA::lacZ and cysJIH::lacZ fusions. Null dnaJ and dnaKdnaJ mutants were impaired in beta-galactosidase expression from both fusions. Efficient complementation of this defect by wild-type alleles present on a low-copy number plasmid was achieved. The presence of the pMH224 plasmid coding for CysB* protein defective in DNA binding lowered beta-galactosidase expression from cysPTWA::lacZ fusion strain harboring wild-type dnaKdnaJ alleles but did not diminish enzyme expression in delta dnaJ and delta dnaKdnaJ strains.

Alleles↗
PubMed2000

Antibiotic susceptibility of Escherichia coli dnaK and dnaJ mutants.

The role of two chaperone proteins, DnaK and the cooperating factor DnaJ, in Escherichia coli antibiotic susceptibility to three antibiotics (a beta-lactam, chloramphenicol, tetracycline) has been studied. It was found that null dnaJ and dnaKdnaJ mutants are impaired in the functions leading to antibiotic susceptibility. The secretion of beta-lactamase to the periplasmic space is diminished in both mutants, and the additive effect of the two mutations was observed. The activity of chloramphenicol acetyltransferase is also impaired in an additive manner in both mutant strains. Tetracycline uptake is changed only in the double deletion mutant. These defects were observed only during incubation at high temperature (42 degrees C). Efficient complementation of some of these defects by the wild-type alleles introduced on low-copy number plasmid was achieved. Minimal inhibitory concentrations and the titer of the wild-type strains, delta dnaJ and delta dnaKdnaJ mutants treated with ampicillin, chloramphenicol, and tetracycline were also determined. Higher susceptibility of both mutants to chloramphenicol and tetracycline, as compared to their wild-type parent, was observed only after 1 h preincubation of cultures at 42 degrees C. On the contrary, both mutants were less susceptible to ampicillin than their parent strain.

Ampicillin↗
PubMed2000

Biosynthesis and secretion of several enzymes in Escherichia coli dnaK and dnaJ mutants.

Escherichia coli null dnaJ and dnaKdnaJ mutants were defective in the biosynthesis and secretion of several enzymes. The synthesis of beta-galactosidase induced in delta dnaJ and delta dnaKdnaJ mutants was abolished at 42 degrees C and significantly decreased at 30 and 37 degrees C. The activity of alkaline phosphatase in the periplasm in both mutant strains at high temperature was lower than in the wild-type strain. The synthesis of b-type cytochromes was defective in two deletion mutants while the synthesis of nitrate reductase-A at 42 degrees C was influenced by dnaK mutation only. The lack of DnaK and DnaJ does not impair the activity of catechol 2,3-dioxygenase irrespective of growth temperature.

Alkaline Phosphatase↗
PubMed1999

Physiological consequences of mutations in Escherichia coli heat shock dnaK and dnaJ genes.

Mutations in the heat shock genes, dnaK and dnaJ, cause severe defects of several cellular functions. Null dnaJ and dnaKdnaJ mutations can be transduced in a restricted range of temperature. The efficiency of transformation with three unrelated plasmids, viz pACYC184, pBR322 and pSC101, is two times lower in dnaK mutants while the dnaJ mutant is characterized by slightly impaired transformation with pSC101 only. The lack of DnaJ function negatively influences the stability of pSC101 at 42 degrees C, and this plasmid cannot be stably maintained at 30 degrees C in the delta dnaKdnaJ mutant. The double deletion mutant, delta dbaKdnaJ, is characterized by impaired osmoadaptation. The galactokinase content is lower in both mutants tested compared with wild-type strains even at 30 degrees C. The efficient complementation of some of these defects by the wild-type alleles present on low-copy number plasmid was achieved.

Adaptation, Physiological↗
PubMed1999

Effect of DnaK and DnaJ proteins deprivation on Escherichia coli response to starvation.

E. coli defects in response to nutritional starvation caused by DnaK and DnaJ proteins deprivation are examined. The ability of delta dnaKdnaJ mutant to survive carbon, nitrogen and phosphorus starvation is highly impaired while delta dnaJ mutant is characterized by the diminished survival of phosphorus starvation only. delta dnaKdnaJ mutant grows slowly utilizing maltose and glycerol and delta dnaJ mutant utilizes glycerol inefficiently. The growth on alternate nitrogen sources is comparable to wild-type strain.

Bacterial Proteins↗
PubMed1997

Escherichia coli defects caused by null mutations in dnaK and dnaJ genes.

Escherichia coli dnaJ and dnaKdnaJ mutants are defective in cell growth and survival at high temperature. Lack of DnaK and DnaJ proteins results in cell filamentation and leads to the defect in motility. Synthesis of DNA and protein is inhibited at 42 degrees C, especially in double-deletion mutant. Degradation of protein was observed in both mutants at high temperature. Complementation of these defects can be achieved by the expression of the wild-type alleles from low-copy number plasmid.

Bacterial Proteins↗
PubMed1997

Escherichia coli defects caused by DnaK and DnaJ proteins overproduction.

Escherichia coli defects caused by the overproduction of DnaK and DnaJ proteins are presented. Induced overproduction of DnaK and DnaJ was determined by SDS-PAGE electrophoresis and immunoblots analysis. Elevated levels of both proteins are not deleterious for such cellular functions as growth, survival and cell morphology. However, instability of pJW14 plasmid (derivative of pACYC184) was observed as the result of dnaKdnaJ operon overexpression.

Colony Count, Microbial↗
PubMed1995

In memoriam.

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History, 20th Century↗
PubMed1990

Restriction map of Thiobacillus versutus plasmid pTAV1.

A restriction map of Thiobacillus versutus plasmid pTAV1 was constructed using EcoRI, BamHI and SalI restriction enzymes. Knowledge of the restriction map is an obligatory starting point for genetic and molecular studies of this, so far cryptic, plasmid.

Deoxyribonuclease BamHI↗