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Formation of a new DNA replication intermediate in novobiocin-treated human melanoma cells
Abstract:
The effect of novobiocin on the formation of DNA replication intermediates in human melanoma cells was investigated. This drug reduces DNA synthesis in all probability by interfering with the DNA gyrases (enzymes that are involved in the supercoiling of the DNA). The single-stranded DNA replication intermediates were released from the parental DNA by lysing the cells in dilute alkali and were then fractionated by agarose gel electrophoresis. In the untreated cells one can detect replication intermediates ranging in size from Okazaki-fragments up to 10 kb. However, in novobiocin-treated cells, apart from the already known intermediates, formation of a new replication intermediate with the size of about 20 kb was also detected. The 20-kb DNA shows a similar discrete appearance in the agarose gel as the 10-kb DNA intermediate.
Insights
Novobiocin, an antibiotic, alters DNA replication intermediates in human melanoma cells. It likely interferes with DNA gyrase, leading to a new 20-kb intermediate during DNA synthesis.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- DNA replication is a fundamental process for cell division.
- DNA gyrase enzymes are crucial for managing DNA supercoiling during replication.
- Novobiocin is an antibiotic known to inhibit DNA gyrase activity.
Purpose of the Study:
- To investigate the impact of novobiocin on DNA replication intermediates in human melanoma cells.
- To understand how novobiocin affects DNA synthesis by potentially targeting DNA gyrase.
Main Methods:
- Human melanoma cells were treated with novobiocin.
- Cells were lysed in dilute alkali to release single-stranded DNA replication intermediates.
- Agarose gel electrophoresis was used to fractionate and analyze DNA intermediates by size.
Main Results:
- Untreated cells showed replication intermediates from Okazaki fragments up to 10 kb.
- Novobiocin treatment resulted in the appearance of a novel 20-kb DNA replication intermediate.
- The 20-kb intermediate exhibited a discrete band on agarose gel, similar to the 10-kb intermediate.
Conclusions:
- Novobiocin interferes with DNA replication in human melanoma cells.
- The drug's effect is likely mediated through inhibition of DNA gyrase.
- A new 20-kb DNA replication intermediate is formed in the presence of novobiocin.