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Loss of activity of transforming deoxyribonucleic acid after uptake by Haemophilus influenzae
Abstract:
Voll, Mary Jane (University of Pennsylvania, Philadelphia), and Sol H. Goodgal. Loss of activity of transforming deoxyribonucleic acid after uptake by Haemophilus influenzae. J. Bacteriol. 90:873-883. 1965.-Transforming deoxyribonucleic acid (DNA) which has been irreversibly removed from solution by competent cells undergoes a progressive loss in marker activity when tested by lysis of the cells and exposure to new recipient cells. The loss of activity is limited and marker-specific, with greater inactivation of those markers with lower efficiencies of transformation. Recipient factors or donor factors which have undergone recombination, as measured by the appearance of linked markers, do not undergo inactivation. The efficiency of transformation can be correlated with the sensitivity of a marker to inactivation after DNA uptake. A mutation which affects the efficiency of transformation is found to increase sensitivity to postuptake inactivation. The rate of inactivation is temperature-dependent. At temperatures of 20 and 45 C, marker inactivation can occur without concomitant recombination. During the uptake process, DNA is retained in an acid-insoluble form, indicating that the fate of Haemophilus influenzae DNA differs from the fate of transforming DNA in pneumococcus.
Insights
Transforming deoxyribonucleic acid (DNA) loses activity after Haemophilus influenzae uptake. This inactivation is marker-specific and temperature-dependent, differing from pneumococcus.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Transforming deoxyribonucleic acid (DNA) mediates genetic exchange in bacteria.
- Understanding DNA fate after cellular uptake is crucial for bacterial genetics.
Purpose of the Study:
- To investigate the stability and activity of transforming DNA after uptake by competent Haemophilus influenzae cells.
- To determine factors influencing DNA inactivation post-uptake.
Main Methods:
- Competent Haemophilus influenzae cells were incubated with transforming DNA.
- Cells were lysed, and DNA activity was assessed using new recipient cells.
- Marker-specific inactivation and recombination were analyzed.
- Temperature-dependent inactivation rates were measured.
Main Results:
- Transforming DNA undergoes progressive marker activity loss after uptake.
- Inactivation is marker-specific, affecting less efficient transformation markers more.
- Recombined DNA (linked markers) showed no inactivation.
- Mutation affecting transformation efficiency increased post-uptake inactivation sensitivity.
- Inactivation occurred without recombination at 20 and 45°C.
Conclusions:
- Haemophilus influenzae exhibits a unique mechanism for handling transforming DNA post-uptake.
- DNA inactivation is linked to transformation efficiency and temperature.
- The fate of DNA in H. influenzae differs from that in other bacteria like pneumococcus.