Structural basis for RNA translocation by DEAH-box ATPases.

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• DEAH-box ATPases are vital spliceosome components involved in pre-mRNA intron excision.
• Previous studies suggested these proteins use translocation for RNA manipulation, but the mechanism remained unclear.

Purpose of the Study:

• To elucidate the translocation mechanism of DEAH-box ATPases, specifically Prp22.
• To identify key conformational states governing ATPase activity and RNA binding.

Main Methods:

• Crystal structure determination of Prp22 in various nucleotide-free states.
• Comparative analysis of Prp22 structures with other DEAH-box ATPases (e.g., Prp43).

Main Results:

• Identified two novel conformational snapshots of Prp22, revealing intrinsic RecA2 domain mobility in the absence of nucleotides and RNA.
• Observed that RNA binding stabilizes a specific open conformation, while nucleotide binding induces a transition between closed and open states.
• Established a model where DEAH-box ATPases translocate 1 nucleotide per ATP hydrolyzed via a 3'-5' motor function.

Conclusions:

• DEAH-box ATPases function as ATP-driven motors, translocating along ssRNA through cyclical conformational changes.
• The conserved motif V serine residue plays a critical role in sensing the catalytic state and regulating RecA2 domain positioning.