A general strategy for engineering GU base pairs to facilitate RNA crystallization.

Area of Science:

• Structural Biology
• Biochemistry
• Molecular Biology

Background:

• X-ray crystallography is crucial for determining RNA atomic structures.
• Achieving high-resolution diffraction from RNA crystals remains a significant challenge.

Purpose of the Study:

• To introduce a straightforward strategy for enhancing the resolution of RNA crystals.
• To improve the success rate of high-resolution RNA structure determination via X-ray crystallography.

Main Methods:

• Selective substitution of Watson-Crick base pairs (GC/AU) with GU pairs in RNA sequences.
• Analysis of resulting RNA crystals using X-ray crystallography to assess resolution enhancement.
• Targeting GU pair placement in specific helical stems (e.g., 5' helical stem or peripheral stems).

Main Results:

• High-resolution structures were obtained for eight unique RNA crystals.
• Six instances demonstrated improved resolution after GC/AU to GU substitution.
• Two cases yielded high-resolution structures from previously poor diffraction data.
• Facilitated first-time structural determination for several complex RNA molecules, including ribozymes and aptamers.

Conclusions:

• Selective GU base pair substitution is an effective strategy to enhance RNA crystal resolution.
• This method simplifies the process of obtaining high-resolution RNA structures.
• The approach is applicable for designing new RNA sequences or selecting suitable homologous sequences for structural studies.