NELF-E RRM undergoes major structural changes in flexible protein regions on target RNA binding

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• The E subunit of human negative transcription elongation factor (NELF-E) possesses a canonical RNA recognition motif (RRM).
• Canonical RRMs typically bind RNA via their beta-sheet surface.
• NELF-E RRM exhibits distinct conformational changes upon RNA binding, involving regions distant from the canonical interface.

Purpose of the Study:

• To determine the solution structure of the NELF-E RRM bound to transactivator responsive element (TAR) RNA.
• To elucidate the conformational changes induced by RNA binding in NELF-E RRM.
• To compare the RNA-bound structure of NELF-E RRM with other RRMs, such as U1A RRM.

Main Methods:

• Nuclear magnetic resonance (NMR) spectroscopy was used to study RNA-induced conformational changes.
• Solution structure determination of the NELF-E RRM in complex with TAR RNA.

Main Results:

• RNA binding to NELF-E RRM induces the formation of a helix in its C-terminal region.
• The RNA-bound conformation of NELF-E RRM closely resembles that of the U1A RRM.
• Unlike U1A RRM, the C-terminus of NELF-E RRM is unstructured in the free state but becomes helical upon RNA binding.

Conclusions:

• RNA binding to NELF-E RRM induces a significant conformational change, forming a C-terminal helix.
• This conformational adaptation results in an RNA-bound structure highly similar to that of U1A RRM.
• NELF-E RRM's flexible C-terminus plays a crucial role in achieving a stable, U1A-like RNA-binding conformation.