Related Experiment Videos
The binding of streptomycin to ribonucleotides
Abstract:
Incubation of streptomycin (SM) with [32P]5'-ribonucleotides at pH 7.0 produces fractions that migrate towards the cathode in high voltage electrophoresis (HVE) separations at pH 3.5. SM appears to interact with pG, pA and pC but not with pU. The appearance of these [32P]-labeled fractions is dependent on incubation time and SM concentration. Incubation of nucleotides with dihydrostreptomycin (DSM) or SM reduced with sodium cyanoborohydride (NaBH3CN) at pH 5.0, does not produce detectable changes in [32P] nucleotide mobility on HVE; however, incubation with SM reduced with NaBH3CN at pH 7.0 does produce [32P]-labeled fractions migrating with a net positive charge. Elution of [32P]-labeled material migrating towards the cathode from SM-5'-nucleotide incubations and re-electrophoresis results in nucleotides migrating with pG, pA and pC markers. These data indicate a reversible interaction between the SM-streptose aldehyde and amino-group containing nucleotides. This type of interaction may form an additional binding site for SM to RNA, relative to DSM.
Insights
Streptomycin (SM) reversibly interacts with guanylate, adenylate, and cytidylate nucleotides, forming new binding sites. This interaction, dependent on SM concentration and time, may enhance SM binding to RNA.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Streptomycin (SM) is a crucial antibiotic targeting bacterial protein synthesis.
- Understanding the precise molecular interactions of SM with nucleic acids is vital for antibiotic development.
- Previous studies suggest SM binds to RNA, but the exact binding mechanisms and sites require further elucidation.
Purpose of the Study:
- To investigate the interaction between streptomycin and 5'-ribonucleotides.
- To determine the chemical basis and specificity of SM-nucleotide binding.
- To explore how these interactions might contribute to SM's binding to RNA.
Main Methods:
- High-voltage electrophoresis (HVE) at pH 3.5 to separate [32P]-labeled 5'-ribonucleotides after incubation with streptomycin (SM).
- Incubation of nucleotides with modified forms of SM, including dihydrostreptomycin (DSM) and reduced SM, at different pH values.
- Analysis of nucleotide mobility shifts and charge changes post-incubation.
Main Results:
- SM incubation with [32P]guanylate, [32P]adenylate, and [32P]cytidylate at pH 7.0 produced fractions migrating cathodically in HVE, indicating interaction.
- No interaction was observed with [32P]uridylate.
- Modified SM forms (DSM or NaBH3CN-reduced SM at pH 5.0) did not alter nucleotide mobility, but NaBH3CN-reduced SM at pH 7.0 induced positively charged fractions.
- Re-electrophoresis confirmed the cathodically migrating fractions contained nucleotides similar to pG, pA, and pC.
Conclusions:
- A reversible interaction occurs between the SM-streptose aldehyde and the amino groups of guanylate, adenylate, and cytidylate.
- This interaction is pH-dependent and specific to certain nucleotides.
- The findings suggest a potential mechanism for an additional SM binding site on RNA, distinct from that of dihydrostreptomycin.