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Non-contact, Label-free Monitoring of Cells and Extracellular Matrix using Raman Spectroscopy
Published on: May 29, 2012
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Multi-wavelength Raman microscopy of nickel-based electron transport in cable bacteria
Bent Smets1, Henricus T S Boschker1,2, Maxwell T Wetherington3
1Department of Biology, University of Antwerp, Antwerp, Belgium.
Frontiers in Microbiology
|March 25, 2024
Summary
Cable bacteria utilize a unique nickel cofactor for long-distance electron transport. Raman microscopy revealed this novel cofactor structure, resembling nickel bis(1,2-dithiolene) complexes.
Area of Science:
- Microbiology
- Biochemistry
- Spectroscopy
Background:
- Cable bacteria conduct long-distance electron transport via conductive protein fibers.
- This unique biological process is mediated by a metalloprotein with a sulfur-coordinated nickel (Ni) cofactor.
- The molecular structure of this Ni-cofactor is currently unknown.
Purpose of the Study:
- To elucidate the molecular structure and organization of the novel Ni-cofactor in cable bacteria.
- To identify cell compounds associated with cable bacterium physiology using advanced Raman microscopy techniques.
Main Methods:
- Multi-wavelength Raman microscopy was employed to analyze native cable bacterium filaments.
- Stable isotope labeling and orientation-dependent Raman microscopy were used to study the Ni-cofactor.
- Selective extraction of conductive fiber networks aided in isolating Ni-cofactor signals.
Main Results:
- Raman spectra revealed vibrational modes from cytochromes, polyphosphate granules, proteins, and the Ni-cofactor.
- Isolated Ni-cofactor modes showed intense, orientation-dependent Raman scattering.
- Thirteen Ni-cofactor modes were identified, with some exhibiting strong signals across multiple wavelengths (405–1,064 nm).
Conclusions:
- The Ni-cofactor structure in cable bacteria is unique and does not resemble known biological Ni-cofactors.
- Results suggest the Ni-cofactor structure is similar to nickel bis(1,2-dithiolene) complexes.
- This study provides crucial insights into the molecular basis of long-distance electron transport in cable bacteria.
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