Effect of blocking protein synthesis at nonpermissive temperatures on temperature-sensitive deoxyribonucleic acid mutants of Escherichia coli

Evans, Ian S.; Forrest, Nancy; Lawrence, Andrea L.; Eberle, Helen

doi:10.1128/jb.140.2.445-451.1979

Cited by 4 publications

(1 citation statement)

References 27 publications

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“…The M. tuberculosis dna Acos mutants, unlike the E. coli dna A46 (ts), show a ‘delayed replication defect’ (slow stop) at the non‐permissive temperature, but recover readily at the permissive temperature (Abe and Tomizawa, 1971; Evans et al ., 1979). DNA synthesis in dna A46 strains can be aligned if cells are allowed to accumulate excess initiation potential at 42°C prior to returning to the permissive temperature.…”

Section: Discussionmentioning

confidence: 99%

Synchronous replication initiation in novel Mycobacterium tuberculosis dnaA cold‐sensitive mutants

Nair

Dziedzic

Greendyke

et al. 2009

Molecular Microbiology

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SummaryThe genetic aspects of oriC replication initiation in Mycobacterium tuberculosis are largely unknown. A two-step genetic screen was utilized for isolating M. tuberculosis dnaA cold-sensitive (cos) mutants. First, a resident plasmid expressing functional dnaA integrated at the attB locus in dnaA null background was exchanged with an incoming plasmid bearing a mutagenized dnaA gene. Next, the mutants that were defective for growth at 30°C, a non-permissive temperature, but resumed growth and DNA synthesis when shifted to 37°C, a permissive temperature, were subsequently selected. Nucleotide sequencing analysis located mutations to different regions of the dnaA gene. Modulation of the growth temperatures led to synchronized DNA synthesis. The dnaA expression under synchronized DNA replication conditions continued to increase during the replication period, but decreased thereafter reflecting autoregulation. The dnaAcos mutants at 30°C were elongated suggesting that they may possibly be blocked during the cell division. The DnaA115 protein is defective in its ability to interact with ATP at 30°C, but not at 37°C. Our results suggest that the optimal cell cycle progression and replication initiation in M. tuberculosis requires that the dnaA promoter remains active during the replication period and that the DnaA protein is able to interact with ATP.

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Section: Discussionmentioning

confidence: 99%

Synchronous replication initiation in novel Mycobacterium tuberculosis dnaA cold‐sensitive mutants

Nair

Dziedzic

Greendyke

et al. 2009

Molecular Microbiology

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Regulation of DNA synthesis and capacity for initiation in DNA temperature sensitive mutants of Escherichia coli

et al. 1982

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The capacity for initiation and subsequent chain elongation was examined in several DNA temperature sensitive mutants of Escherichia coli after the mutants had been held at nonpermissive temperature for approximately 1.5 generation equivalents and then returned to permissive temperature in the presence of chloramphenicol. The results obtained indicate that 4-5 sets of replication forks can be initiated after return to permissive temperature in the presence of chloramphenicol but the forks apparently become stalled and fail to complete chromosomal replication in the presence of chloramphenicol. In temperature reversible dnaA mutants, once the chloramphenicol is removed the forks appear to be able to resume replication at the nonpermissive temperature. The relationship between premature initiation and premature chain termination is discussed.

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Regulation of DNA synthesis and capacity for initiation in DNA temperature sensitive mutants of Escherichia coli

Eberle

Forrest

1982

Molec. Gen. Genet.

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This paper deals with the conditions that are necessary for the acquisition and expression of initiation potential in dnaA temperature sensitive mutants after they have been held for periods of time at nonpermissive temperature and then returned to permissive temperature in the presence of chloramphenicol. The following conditions were found to be essential: (1) 40-60 min at nonpermissive temperature during which time protein synthesis must occur; this period must be followed by (2) return to permissive temperature under which conditions active dnaA product is present, and (3) protein synthesis must be blocked during the first 10-20 min immediately after return to permissive temperature (when initiation takes place). In order for expression of the initiation potential (4) the chloramphenicol must be removed to allow the progression of the replication forks which had been initiated to occur and (5) the recA+ phenotype appears to be required for acquisition or expression (or both) of the initiation potential.

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Effect of blocking protein synthesis at nonpermissive temperatures on temperature-sensitive deoxyribonucleic acid mutants of Escherichia coli

Cited by 4 publications

References 27 publications

Synchronous replication initiation in novel Mycobacterium tuberculosis dnaA cold‐sensitive mutants

Synchronous replication initiation in novel Mycobacterium tuberculosis dnaA cold‐sensitive mutants

Regulation of DNA synthesis and capacity for initiation in DNA temperature sensitive mutants of Escherichia coli

Regulation of DNA synthesis and capacity for initiation in DNA temperature sensitive mutants of Escherichia coli

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