Imaging whole Escherichia coli bacteria by using single-particle x-ray diffraction.

Area of Science:

• Structural Biology
• Biophysics
• Microscopy

Background:

• Coherent x-ray diffraction (CXD) offers high-resolution imaging potential for biological samples.
• Imaging intact cells with CXD presents challenges due to sample complexity and data analysis.

Purpose of the Study:

• To report the first experimental recording of diffraction patterns from intact Escherichia coli bacteria using coherent x-rays.
• To reconstruct a real-space image of the bacteria at high resolution using advanced phasing methods.
• To demonstrate the capability of CXD for visualizing intracellular structures.

Main Methods:

• Utilized coherent x-rays with a 2 A wavelength for diffraction pattern recording.
• Employed the oversampling phasing method for direct reconstruction of real-space images.
• Used manganese oxide labeling to identify protein distribution within bacteria.
• Confirmed results with fluorescence microscopy.

Main Results:

• Successfully recorded diffraction patterns from intact Escherichia coli.
• Reconstructed a 30 nm resolution image of the bacteria.
• Achieved a high-quality reconstruction with an R factor of approximately 5%.
• Visualized the distribution of labeled proteins within the bacteria.

Conclusions:

• The study demonstrates the feasibility of high-resolution 3D imaging of whole, intact bacteria using CXD.
• This diffraction-based approach surpasses limitations of lens-based microscopy for thicker biological samples.
• The findings represent a significant advancement towards imaging single biomolecules at near-atomic resolution.