4DKK: The X-ray Crystal Structure of the Human Stau1 Ssm-'rbd'5 Domain- Swapped Dimer

Staufen1 (STAU1)-mediated mRNA decay (SMD) degrades mammalian-cell mRNAs that bind the double-stranded RNA (dsRNA)-binding protein STAU1 in their 3' untranslated region. We report a new motif, which typifies STAU homologs from all vertebrate classes, that is responsible for human STAU1 (hSTAU1) homodimerization. Our crystal structure and mutagenesis analyses reveal that this motif, which we named the Staufen-swapping motif (SSM), and the dsRNA-binding domain 5 ('RBD'5) mediate protein dimerization: the two SSM alpha-helices of one molecule interact primarily through a hydrophobic patch with the two 'RBD'5 alpha-helices of a second molecule. 'RBD'5 adopts the canonical alpha-beta-beta-beta-alpha fold of a functional RBD, but it lacks residues and features required to bind duplex RNA. In cells, SSM-mediated hSTAU1 dimerization increases the efficiency of SMD by augmenting hSTAU1 binding to the ATP-dependent RNA helicase hUPF1. Dimerization regulates keratinocyte-mediated wound healing and many other cellular processes.
PDB ID: 4DKKDownload
MMDB ID: 108402
PDB Deposition Date: 2012/2/3
Updated in MMDB: 2013/05 
Experimental Method:
x-ray diffraction
Resolution: 1.7  Å
Source Organism:
Similar Structures:
Biological Unit for 4DKK: dimeric; determined by author and by software (PISA)
Molecular Components in 4DKK
Label Count Molecule
Proteins (2 molecules)
Double-stranded RNA-binding Protein Staufen Homolog 1
(Gene: STAU1)
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB