Structural basis of high-order oligomerization of the cullin-3 adaptor SPOP.

Protein ubiquitination in eukaryotic cells is mediated by diverse E3 ligase enzymes that each target specific substrates. The cullin E3 ligase complexes are the most abundant class of E3 ligases; they contain various cullin components that serve as scaffolds for interaction with substrate-recruiting adaptor proteins. SPOP is a BTB-domain adaptor of the cullin-3 E3 ligase complexes; it selectively recruits substrates via its N-terminal MATH domain, whereas its BTB domain mediates dimerization and interactions with cullin-3.

The structure of the Bach2 POZ-domain dimer reveals an intersubunit disulfide bond.

Bach2 is a transcriptional repressor that is expressed during specific stages of B-cell development and in neuronal cells. It plays a critical role in modulating class-switch recombination during the differentiation of mature B cells to antibody-secreting plasma cells and it is also an important regulator of apoptotic responses to oxidative stress. Bach2 has been implicated both as an oncogene and as a tumour suppressor in human malignancy.

Structure of the wild-type human BCL6 POZ domain.

BCL6 is a transcriptional repressor that is overexpressed in diffuse large B-cell lymphoma and follicular lymphoma. The N-terminal POZ domain of BCL6 interacts with transcriptional corepressors and targeting these associations is a promising therapeutic strategy. Previous structural studies of the BCL6 POZ domain have used a mutant form because of the low solubility of the wild-type recombinant protein.