Visualization of RNA crystal growth by atomic force microscopy

Area of Science:

• Biophysics
• Crystallography
• Molecular Biology

Background:

• Crystallization is crucial for determining the structure of biomolecules like transfer RNA (tRNA).
• Understanding crystal growth mechanisms is essential for optimizing crystallization techniques.
• In situ observation methods provide dynamic insights into crystal formation processes.

Purpose of the Study:

• To investigate the in situ crystallization of yeast tRNAPhe using atomic force microscopy (AFM).
• To observe and analyze the temperature-dependent growth mechanisms of nucleic acid crystals.
• To correlate crystal growth kinetics with supersaturation and identify structural features.

Main Methods:

• Utilized in situ atomic force microscopy (AFM) to image crystal growth.
• Studied hexagonal yeast tRNAPhe crystals over a temperature range of 4 to 16 degrees C.
• Recorded lattice resolution images of surface molecular structures.

Main Results:

• Observed crystal growth occurring at steps on vicinal hillocks driven by screw dislocations.
• Identified a transition in growth mechanisms from step-flow to two-dimensional nucleation around 13.5 degrees C.
• Noted the appearance of three-dimensional nuclei at 12 degrees C.
• Characterized anisotropic step movement and observed transformations in growth modes.
• Acquired high-resolution images of the molecular structure of crystal surface layers.

Conclusions:

• Crystal growth mechanisms of tRNA are strongly temperature-dependent.
• Supersaturation levels influence the observed changes in growth modes.
• AFM provides direct visualization of dynamic processes in nucleic acid crystallization.
• Findings can inform strategies for improved control and optimization of nucleic acid crystallization.