Molecular structure of human TFIIH

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• Transcription factor II H (TFIIH) is a crucial multiprotein complex.
• TFIIH plays essential roles in both gene transcription and DNA repair pathways.

Purpose of the Study:

• To determine the structural organization of human TFIIH.
• To visualize the arrangement of TFIIH subunits at high resolution.

Main Methods:

• Single-particle electron microscopy was employed to image human TFIIH.
• Advanced image processing techniques were utilized to resolve the complex's structure.
• Immunolabeling experiments were performed to localize specific subunits.

Main Results:

• Human TFIIH was visualized at a resolution of 3.8 nm, revealing a distinct ring-like structure with a protruding domain.
• A five-subunit core complex formed a circular architecture, mirroring the ring of the full TFIIH complex.
• Subunit localization identified p44 at the base of the protruding domain, flanked by XPB and XPD helicases within the ring.

Conclusions:

• A quaternary organizational model for TFIIH was proposed based on the structural and localization data.
• The findings provide insights into the architecture of a key complex involved in fundamental cellular processes.