Aleksandra Blinkowa

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A new conditional thermosensitive Hfr mutant of Escherichia coli K-12 was isolated. The ts mutation is cotransducible with purE and tsx loci on the E. coli chromosome. Upon temperature shift to 42 degrees C the DNA synthesis and transfer of chromosome is stopped immediately and RNA, protein synthesis in about ten minutes.
The Escherichia coli dnaX gene encodes both the tau and gamma subunits of DNA polymerase III holoenzyme in one reading frame. The 71.1 kDa tau and the shorter gamma share N-terminal sequences. Mutagenesis of a potential ribosomal frameshift signal located at codons 428-430 without changing the amino acid sequence of the tau product, eliminated detectable(More)
A dnaW mutant, isolated on the basis of inability to effect conjugal DNA transfer at high temperature, has been shown by complementation and enzyme assay to be defective in the adk (adenylate kinase; EC locus. The adk mutant, known to have reduced ATP concentration at the nonpermissive temperature (Cousin and Belaich 1966), was used to demonstrate(More)
The Escherichia coli 2.2 kilobase dnaZX region contains one 1929 nucleotide reading frame which directs the synthesis of two protein products involved in DNA polymerization. The larger consists of 643 amino acids in a deduced 71,114 dalton chain which could be the tau subunit of DNA polymerase III. The smaller, the DNA polymerase III gamma subunit, is(More)
Suppressor mutations located within dnaA can suppress the temperature sensitivity of a dnaZ polymerization mutant, indicating in vivo interaction of the products of these genes. The suppressor allele of dnaA [designated dnaA(SUZ, Cs)] could not be introduced, even at the permissive temperature, by transduction into temperature-sensitive (Ts) dnaC or dnaG(More)
Suppressors of a temperature-sensitive dnaZ polymerization mutant of Escherichia coli have been identified by selecting temperature-insensitive revertants. Those suppressed strains which concomitantly became cold sensitive were chosen for further study. Intragenic suppressor mutations, which caused cold-sensitive defects in DNA polymerization, were located(More)
Numerous facultative temperature sensitive recombination deficient mutants of Escherichia coli K-12 strain 108 were isolated after mutagenization with nitrosoguanidine. The majority of the mutants were resistant to UV irradiation. Three mutants, KBP72, KBP169 and KBP610, with marked recombination deificiency (300 to 15,000 times) at 42 degrees C, were UV(More)
The possible role of DNA polimerase III in conjugation was studied in a series of mutants temperature-sensitive for DNA polymerase III synthesis. The temperature-sensitive DNA mutation called dnaE 486 (ts) prohibits vegetative DNA replication at 41-45 degrees. Transfer of episome and chromosome from temperature-sensitive donor, carrying dnaE mutation to(More)