PDBsum entry 3m5b

Transcription

PDB id: 3m5b

Contents

Protein chains

109 a.a.

Waters ×154

References listed in PDB file

Key reference

• Title: Insights into strand exchange in btb domain dimers from the crystal structures of fazf and miz1.
• Authors: P.J.Stogios, J.A.Cuesta-Seijo, L.Chen, N.C.Pomroy, G.G.Privé.
• Ref.: J Mol Biol, 2010, 400, 983-997.
• PubMed id: 20493880

Abstract

The BTB domain is a widely distributed protein-protein interaction motif that is often found at the N-terminus of zinc-finger transcription factors. Previous crystal structures of BTB domains have revealed tightly interwound homodimers, with the N-terminus from one chain forming a two stranded antiparallel beta-sheet with a strand from the other chain. We have solved the crystal structures of the BTB domains from FAZF and Miz1 to resolutions of 2.0 A and 2.6 A, respectively. Unlike previous examples of BTB domain structures, the FAZF BTB domain is a non-swapped dimer with each N-terminal beta-strand associated with its own chain. As a result, the dimerization interface in the FAZF BTB domain is about half as large as in the domain-swapped dimers. The Miz1 BTB domain resembles a typical swapped BTB dimer, although it has a shorter N-terminus that is not able to form the interchain sheet. Using cysteine crosslinking, we confirmed that the PLZF BTB dimer is strand-exchanged in solution while the FAZF BTB dimer is not. A phylogenic tree of the BTB fold based on both sequence and structural features shows that the common ancestor of the BTB domain in the BTB-ZF proteins was a domain-swapped dimer. The differences in the N-termini seen in the FAZF and Miz1 BTB domains appear to be more recent developments in the structural evolution of the domain.