he Structural Biology and Cancer Lab primarily uses NMR for biomolecular structural characterization and incorporates complementary structural and functional studies through collaborations. This integrative structural and functional approach is indispensable to understand protein complexes relevant in chromatin remodeling and DNA replication and repair. We study the INhibitor of Growth (ING1-5) family of tumor suppressors, which restrict cell growth and induce apoptosis through transcription regulation. They form interaction networks, binding histone H3 tails and recruiting Histone Acetyl Transferase (HAT) and Histone Deacetylase (HDAC) complexes to the chromatin. The lab has characterized the structure of ING4 as a dimeric protein that recognizes histone H3 trimethylated at lysine 4 through its PlantHomeoDomain (PHD). Structure-sequence alignments suggest that homodimerization of other ING proteins, and even heterodimerization, may occur, especially between the highly homologous ING4 and ING5. The team is characterizing the structure of ING5 and its N-terminal domain, and the possible formation of heterodimers and also is studing the structural and functional implications of ING5 mutants detected in cancer. PCNA is a DNA sliding clamp, an essential factor for DNA replication and repair. It has a ring-shape structure and interacts with many proteins, including ING1. The group found by NMR that some interactions are extremely weak in solution, likely mediated by other factors in the cell. The PCNA associated factor p15 is overexpressed in cancer, with high levels correlating with poor prognosis, and becomes ubiquitylated upon DNA damage and also found that p15 is an intrinsically disordered protein that binds and threads through the PCNA channel with its N- and C-terminal tails remaining disordered at both sides of the ring. P15 binds simultaneously and independently to DNA, suggesting a regulation of PCNA sliding velocity on the DNA. This might facilitate the switch from replicative to translesion synthesis polymerase binding at stalled replication forks. The lab is investigating the structure and binding properties of ubiquitylated p15.
Life & Medical Sciences
- Biosciences & Health
- NMR for biomolecular structural characterization