Related Experiment Videos
Complexes formed between calmodulin and the antagonists J-8 and TFP in solution
C J Craven1, B Whitehead, S K Jones
1Department of Molecular Biology and Biotechnology, University of Sheffield, U.K.
Biochemistry
|August 13, 1996
Summary
The study investigated how drugs bind to calmodulin (CaM). Researchers found that drug molecules bind to each CaM domain independently, challenging the idea that drug tails link domains.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Calmodulin (CaM) is a crucial calcium-binding protein involved in cellular signaling.
- Antagonists like J-8 and trifluoperazine (TFP) are known to bind CaM, but their precise binding modes require further elucidation.
Purpose of the Study:
- To investigate the binding interactions of N-(8-aminooctyl)-5-iodonaphthalene-1-sulfonamide (J-8) and trifluoperazine (TFP) with bovine calmodulin (CaM).
- To determine the binding mode of J-8 to the C-terminal domain (tr2c) of CaM.
- To clarify the role of the drug's flexible tail in CaM binding.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy, including NOESY data.
- Mobility measurements.
- Chemical shift and line-shape analysis.
Main Results:
- The primary interaction involves the naphthalene ring of J-8 binding to a hydrophobic pocket in tr2c, similar to CaM target peptides.
- Binding of J-8 to intact CaM shows no significant change in binding mode compared to J-8.tr2c, with one drug molecule per domain.
- The aliphatic amino tail of J-8 remains highly mobile, refuting the hypothesis that it bridges CaM domains.
- TFP induces similar chemical shifts to J-8, indicating a comparable binding mode.
- Stoichiometry is one drug molecule per CaM domain, with evidence of secondary binding sites.
Conclusions:
- J-8 and TFP bind to CaM with a 1:1 stoichiometry per domain.
- The flexible tail of J-8 does not bridge CaM domains.
- The findings provide detailed insights into the molecular interactions between CaM and its antagonists.