Which antibiotic inhibits DNA and RNA synthesis?

Rifamycins and quinolones are two primary classes of antibiotics that inhibit DNA and RNA synthesis in bacteria.

Antibiotics Inhibiting Nucleic Acid Synthesis

Several antibiotics target bacterial DNA and RNA synthesis, crucial processes for bacterial survival and replication. These antibiotics disrupt these processes through various mechanisms. According to the provided reference, two major classes accomplish this:

• Rifamycins: These antibiotics inhibit bacterial RNA polymerase, the enzyme responsible for transcribing DNA into RNA. By binding to RNA polymerase, rifamycins prevent the initiation of transcription, thereby halting RNA synthesis.

• Quinolones and Fluoroquinolones: This group of antibiotics inhibits DNA gyrase and topoisomerase IV, enzymes essential for DNA replication, repair, and transcription. These enzymes manage DNA supercoiling, a process necessary for accessing the genetic code. By inhibiting these enzymes, quinolones lead to DNA breakage and cell death.

How These Antibiotics Work

Here's a more detailed look at their mechanisms of action:

• Rifamycins (e.g., Rifampin):

  • Bind to the bacterial RNA polymerase enzyme.
  • Block the elongation phase of transcription.
  • Effective against Mycobacterium tuberculosis and other bacteria.
  • Example: Rifampin is a common example used to treat tuberculosis.

• Quinolones and Fluoroquinolones (e.g., Ciprofloxacin):

  • Target DNA gyrase and topoisomerase IV.
  • Prevent DNA from unwinding and replicating properly.
  • Lead to DNA strand breaks.
  • Example: Ciprofloxacin is a fluoroquinolone used for various bacterial infections.

Table Summary

Antibiotic Class	Mechanism of Action	Target Enzymes/Molecules	Examples
Rifamycins	Inhibits RNA synthesis	Bacterial RNA polymerase	Rifampin
Quinolones/Fluoroquinolones	Inhibits DNA replication and repair	DNA gyrase, Topoisomerase IV	Ciprofloxacin