Mitomycin C induction of a temperate phage in Pseudomonas aeruginosa

1968 ◽  
Vol 14 (6) ◽  
pp. 667-673 ◽  
Author(s):  
T. Yamamoto ◽  
C. T. Chow

After addition of mitomycin C to Pseudomonas aeruginosa strain MAC-264 cells, DNA synthesis stops but resumes again after 45 min. This resumption in DNA synthesis is due to the induction of a temperate phage. Early after induction, both RNA and protein syntheses continue but later on little or no net synthesis of these macromolecules occurs. Cell lysis occurs at 90 to 105 min after addition of mitomycin C. Analysis of the lysates indicates that a DNA phage with an icosahedral head about 55 mμ in diameter with a short wedge-shaped tail is produced. This phage [Formula: see text] has a buoyant density of 1.468 g/ml in CsCl. The guanine + cytosine content of the phage DNA determined by its buoyant density in CsCl is 46% compared to 68% for the host DNA.Some phage tail-like structures which have a buoyant density of 1.305 g/ml in CsCl are also induced at the same time.

2017 ◽  
Vol 114 (12) ◽  
pp. E2310-E2318 ◽  
Author(s):  
Bin Zhu ◽  
Longfei Wang ◽  
Hitoshi Mitsunobu ◽  
Xueling Lu ◽  
Alfredo J. Hernandez ◽  
...  

2018 ◽  
Vol 90 (24) ◽  
pp. 14462-14468 ◽  
Author(s):  
Yong He ◽  
Yanli Shi ◽  
Mengli Liu ◽  
Yingran Wang ◽  
Lin Wang ◽  
...  

1970 ◽  
Vol 15 (2) ◽  
pp. 147-156 ◽  
Author(s):  
B. A. Bridges ◽  
Rachel E. Dennis ◽  
R. J. Munson

SUMMARYA system has been developed for the study of reversion of an amber mutation responsible for a deficiency in DNA synthesis in T4 phage E51. When complexed with bacteria able to suppress the amber mutation the induced mutation rate per phage genome per rad isWhen complexed with bacteria unable to suppress the amber mutation (and being thus unable to synthesize phage DNA) the induced mutation rate is at least 14 times lower indicating that DNA synthesis is necessary for the production of the majority of functional reversions at the amber site. The induced mutation rate in suppressor-containing bacteria is independent of multiplicity of infection between 0·2 and 5, suggesting that recombination immediately after irradiation between phage genomes is unlikely to be a requirement for the mutation process.


1964 ◽  
Vol 17 (3) ◽  
pp. 719 ◽  
Author(s):  
CI Davern

An enrichment procedure for the isolation of RNA bacteriophage is described. The method involves the inoculation of sewage samples into cultures of Escherichia coli K-12 Hfr under conditions where DNA synthesis is restricted by the addition of 5-fiuorodeoxyuridine to the culture medium. Six phage isolates were made and all of them were shown to be male-specific. One of the male-specific phage was further characterized as an RNA phage, having very similar properties to RNA phage already isolated in other parts oftha world. This RNA phage has a buoyant density of 1�42 g/cm3 in caesium chloride. and has a sedimentation coefficient of 79'5 Sin O'Ol:M Tria-HOI buffer, pH 7� 4, at 20�0.


1992 ◽  
Vol 70 (7) ◽  
pp. 605-608 ◽  
Author(s):  
Giselle Sanchez ◽  
Margaret D. Mamet-Bratley

The development of bacteriophage T7 was examined in an Escherichia coli double mutant defective for the two major apurinic, apyrimidinic endonucleases (exonuclease III and endonuclease IV, xth nfo). In cells infected with phages containing apurinic sites, the defect in repair enzymes led to a decrease of phage survival and a total absence of bacterial DNA degradation and of phage DNA synthesis. These results directly demonstrate the toxic action of apurinic sites on bacteriophage T7 at the intracellular level and its alleviation by DNA repair. In addition, untreated T7 phage unexpectedly displayed reduced plating efficiency and decreased DNA synthesis in the xth nfo double mutant.Key words: apurinic sites, DNA repair, T7 phage.


2005 ◽  
Vol 187 (17) ◽  
pp. 6058-6068 ◽  
Author(s):  
Weihui Wu ◽  
Shouguang Jin

ABSTRACT In a search for regulatory genes of the type III secretion system (TTSS) in Pseudomonas aeruginosa, transposon (Tn5) insertional mutants of the prtR gene were found defective in the TTSS. PrtR is an inhibitor of prtN, which encodes a transcriptional activator for pyocin synthesis genes. In P. aeruginosa, pyocin synthesis is activated when PrtR is degraded during the SOS response. Treatment of a wild-type P. aeruginosa strain with mitomycin C, a DNA-damaging agent, resulted in the inhibition of TTSS activation. A prtR/prtN double mutant had the same TTSS defect as the prtR mutant, and complementation by a prtR gene but not by a prtN gene restored the TTSS function. Also, overexpression of the prtN gene in wild-type PAK had no effect on the TTSS; thus, PrtN is not involved in the repression of the TTSS. To identify the PrtR-regulated TTSS repressor, another round of Tn mutagenesis was carried out in the background of a prtR/prtN double mutant. Insertion in a small gene, designated ptrB, restored the normal TTSS activity. Expression of ptrB is specifically repressed by PrtR, and mitomycin C-mediated suppression of the TTSS is also abolished in a ptrB mutant strain. Therefore, PtrB is a new TTSS repressor that coordinates TTSS repression and pyocin synthesis under the stress of DNA damage.


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