Selenium derivatization of nucleic acids for X-ray crystal-structure and function studies.

Area of Science:

• Structural Biology
• Biochemistry
• Crystallography

Background:

• Protein crystallography widely uses selenium derivatization (selenomethionine) for structure determination via multi-wavelength anomalous dispersion (MAD) phasing.
• This technique has been successfully adapted for nucleic acids, creating selenium-derivatized nucleic acids (SeNA).

Purpose of the Study:

• To review recent advancements in atomic site-specific selenium derivatization of nucleic acids.
• To highlight the application of SeNA in structure determination and functional studies.
• To discuss the advantages of SeNA over conventional methods in X-ray crystallography.

Main Methods:

• Selenium incorporation into nucleic acids by replacing oxygen atoms at various positions (2', 4', 5', nucleobases, phosphates).
• Solid-phase chemical synthesis and enzymatic methods for SeNA production.
• Purification using HPLC, FPLC, and gel electrophoresis.
• Phase determination using MAD phasing.

Main Results:

• SeNA facilitates phase determination via MAD phasing without significant perturbation.
• Se derivatization enhances crystallization, particularly when incorporated at the 2'-position.
• Advantages over halogen derivatization include more modification sites, improved X-ray stability, and structure isomorphism.
• Numerous DNA, RNA, and protein-nucleic acid complex structures determined using SeNA and MAD phasing.

Conclusions:

• Selenium derivatization offers a powerful strategy for phase determination and high-quality crystal growth in nucleic acid crystallography.
• SeNA creates novel nucleic acid properties, establishing a new paradigm in the field.
• This approach provides rational solutions for complex structural and functional studies of nucleic acids.