Related Experiment Video
Updated: Aug 16, 2026
07:56
Sample Preparation of Mycobacterium tuberculosis Extracts for Nuclear Magnetic Resonance Metabolomic Studies
Published on: September 3, 2012
EFFECT OF ETHAMBUTOL ON NUCLEIC ACID METABOLISM IN MYCOBACTERIUM SMEGMATIS AND ITS REVERSAL BY POLYAMINES AND
Journal of Bacteriology
|May 1, 1965
Summary
Ethambutol inhibits Mycobacterium smegmatis growth by interfering with RNA metabolism. Polyamines and magnesium ions reverse this effect, suggesting a role in nucleic acid turnover.
Area of Science:
- Microbiology
- Biochemistry
Background:
- Ethambutol is a key drug for treating tuberculosis.
- Understanding its mechanism of action is crucial for combating drug resistance.
Purpose of the Study:
- To investigate the effect of ethambutol on nucleic acid metabolism in Mycobacterium smegmatis.
- To explore the role of polyamines and divalent cations in reversing ethambutol's inhibitory effects.
Main Methods:
- Monitoring nucleic acid and protein synthesis using radiolabeled precursors (S35 and P32) in Mycobacterium smegmatis cultures.
- Assessing the impact of ethambutol, polyamines, and magnesium ions on bacterial growth and macromolecular synthesis.
Main Results:
- Ethambutol inhibited deoxyribonucleic acid (DNA) and protein synthesis, while only depressing ribonucleic acid (RNA) synthesis.
- Inhibited cells showed a prolonged lag phase and became deficient in RNA.
- Polyamines and magnesium ions shortened the lag phase, increased the minimal inhibitory concentration of ethambutol, and reversed its inhibitory effects.
Conclusions:
- Ethambutol likely inhibits Mycobacterium smegmatis by interfering with the function of polyamines and divalent cations in RNA metabolism.
- Polyamines and divalent cations play a significant role in nucleic acid turnover and can counteract ethambutol's effects.
Related Concept Videos
01:15Drugs that Stabilize Microtubules
Microtubules are dynamic structures that undergo cycles of catastrophe and rescue. The microtubules play a central role in cell division by forming the spindle apparatus for segregating the chromosomes. This makes them ideal targets for regulating dividing cells in tumors and malignant cancer cells. Microtubule stabilizing drugs help stabilize the microtubule formation and promote its polymerization. Paclitaxel was the first microtubule stabilizing agent used as anticancer drug in chemotherapy...
01:10Drugs that Destabilize Microtubules
Microtubules are dynamic structures and can be regulated by microtubule targeting agents (MTAs). Microtubule destabilizing drugs are a class of MTAs that destabilize and prevent microtubules' polymerization. Both natural and synthetic chemicals can be found under this class of drugs. Vincristine and vinblastine, two vinca alkaloids, and colchicine were among the first to be discovered. These drugs can affect cells in various ways, either by inducing a change in cell morphology, preventing...
01:28Biosynthesis of Nucleic Acids
Nucleic acid biosynthesis is a fundamental biochemical process that produces the purine and pyrimidine nucleotides essential for DNA and RNA synthesis. This pathway maintains a balanced nucleotide pool, preventing imbalances that could jeopardize genetic integrity and cellular function. Given the crucial role of nucleotides, their synthesis is tightly regulated to ensure proper cellular homeostasis.Purine BiosynthesisThe biosynthesis of purine nucleotides begins with ribose-5-phosphate, a...
01:25Inhibitors of Bacterial Protein Synthesis
Aminoglycosides constitute a highly potent class of bactericidal antibiotics that exert their antimicrobial effects by targeting the bacterial ribosome, specifically disrupting protein synthesis. These polycationic molecules consist of amino-modified sugars linked via glycosidic bonds to an aminocyclitol core such as 2-deoxystreptamine or streptamine. Their strong positive charges facilitate tight binding to the negatively charged phosphate backbone of ribosomal RNA (rRNA), primarily at the 16S...
01:28Inhibitors of Bacterial DNA Synthesis
Bacterial pathogens depend on precise and efficient DNA replication to sustain infection. Two type II topoisomerases—DNA gyrase and topoisomerase IV—are critical to this process, as they resolve DNA supercoiling and unlink chromosomes during replication. Fluoroquinolones, synthetic derivatives of quinolones, exploit this mechanism by stabilizing the transient DNA–enzyme cleavage complex, preventing strand religation, and causing lethal double-strand breaks. These antibiotics are selectively...