Repeated tertiary fold of RNA polymerase II and implications for DNA binding

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• RNA polymerase II (Pol II) is crucial for gene transcription in eukaryotes.
• Understanding Pol II structure is key to deciphering its regulatory mechanisms.

Purpose of the Study:

• To investigate the structural relationship between the two largest subunits of yeast RNA polymerase II.
• To propose a model for DNA binding within the yeast RNA polymerase II complex.

Main Methods:

• X-ray diffraction analysis of two crystalline forms of yeast RNA polymerase II.
• Comparison of structural data with secondary structure predictions.

Main Results:

• The two largest subunits, Rpb1 and Rpb2, exhibit evidence suggesting similar protein folds.
• A potential DNA binding site located between Rpb1 and Rpb2 is identified.
• The proposed DNA binding mode involves alignment with a pseudo 2-fold axis of the enzyme.

Conclusions:

• The Rpb1 and Rpb2 subunits of yeast RNA polymerase II likely possess homologous structures.
• This structural arrangement facilitates DNA binding, a critical step in transcription initiation.