1H, 15N resonance assignment and three-dimensional structure of CYP1 (HAP1) DNA-binding domain

Area of Science:

• Molecular Biology
• Structural Biology
• Yeast Genetics

Background:

• CYP1 (HAP1) is a yeast transcriptional activator crucial for aerobic metabolism.
• Its DNA-binding domain belongs to the zinc cluster family, characterized by a bimetal thiolate cluster coordinated by cysteine residues.
• Known zinc cluster proteins like GAL4 and PPR1 bind DNA as dimers, recognizing specific CGG motifs.

Purpose of the Study:

• To investigate the structural properties of the CYP1 zinc-cluster region, linker peptide, and dimerization helix.
• To elucidate the DNA-binding mechanism of CYP1, particularly its target site recognition.
• To compare CYP1's structure and potential DNA interaction with other zinc cluster proteins.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy (1H, 15N, 113Cd) was used to analyze a CYP1 fragment (residues 56-126).
• Structural calculations were performed for the zinc-cluster region (residues 60-100).
• Comparison of structural features with known GAL4 and PPR1 DNA-binding domains.

Main Results:

• The six cysteine residues in the CYP1 fragment successfully chelate two cadmium ions, similar to GAL4 and PPR1.
• The zinc-cluster region (residues 60-100) adopts an overall fold conserved with GAL4 and PPR1.
• The linker peptide and dimerization helix were found to be unstructured under the experimental conditions, while DNA-interacting side-chains in the zinc-cluster are conserved.

Conclusions:

• The CYP1 zinc-cluster region likely recognizes a CGG triplet, analogous to GAL4 and PPR1.
• CYP1's unique properties and target site recognition may be determined by the structural characteristics of its linker peptide and/or dimerization helix.
• Further investigation into the linker and helix structures is warranted to fully understand CYP1's transcriptional activation specificity.