Borate binding to siderophores: structure and stability.
Wesley R Harris1, Shady A Amin, Frithjof C Küpper
1Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182-1030, USA.
Journal of the American Chemical Society
|September 14, 2007
Summary
Certain siderophores bind boron, not just iron. This unexpected affinity, dependent on specific chemical groups, suggests roles in marine cell signaling and boron uptake.
Area of Science:
- Biochemistry
- Environmental Chemistry
- Microbiology
Background:
- Siderophores are bacterial iron chelators.
- Boron is essential in marine environments.
- Boron's biological roles are not fully understood.
Purpose of the Study:
- Investigate siderophore-boron interactions.
- Determine the structural requirements for boron binding.
- Explore potential biological functions of boron-siderophore complexes.
Main Methods:
- Electrospray ionization mass spectrometry (ESI-MS).
- Multinuclear Nuclear Magnetic Resonance (NMR) spectroscopy.
- Density Functional Theory (DFT) calculations.
- Measurement of boron binding constants.
Main Results:
- Siderophores with citrate or catecholate groups bind boron.
- Boron complexes with vibrioferrin, rhizoferrin, and petrobactin characterized.
- Significant boron binding constants measured at oceanic pH.
- Boron binding induces a distinct siderophore conformation.
Conclusions:
- Specific siderophores exhibit unexpected boron affinity.
- Boron-siderophore complexes may form in marine environments.
- Potential roles in biological boron uptake and cell signaling hypothesized.
- Conformational changes allow differentiation between iron and boron binding roles.
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