[Show abstract][Hide abstract] ABSTRACT: Human ankyrin repeat and suppressor of cytokine signaling box protein 9 (hASB9) is a specific substrate-recognition subunit of an elongin C-cullin-SOCS box E3 ubiquitin ligase complex. It recognizes its substrate, brain type creatine kinase (CKB), using the ankyrin repeat domain; and facilitates the polyubiquitination of CKB to mediate proteasomal degradation through the SOCS box domain. HASB9-2 is an isoform of hASB9 that contains one ankyrin repeat domain. In this study, the crystal structure of hASB9-2 is shown at 2.2-Å resolution using molecular replacement. Overall, hASB9-2 forms a slightly curved arch with a characteristic L-shaped cross-section. Amino acid substitution analysis based on docking experiments revealed that His103 and Phe107 in hASB9-2 are essential for binding to CKB. Analysis of truncation mutants demonstrated that the first six ankyrin repeats along with the N-terminal region of hASB9-2 contribute to the interaction with CKB.
The Protein Journal 03/2012; 31(4):275-84. · 1.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Synbindin is one component of Transport protein particle (TRAPP) complexes. In the hippocampal neurons, synbindin binds syndecan-2 by its atypical PDZ domain (APD) and may regulate the formation of dendritic spines. To investigate the interaction of synbindin and syndecan-2, we determined the solution structure of the synbindin APD by NMR. The structure of APD is different from the classical canonical PDZ domains by lacking the typical alphaA helix and the signature sequence Gly-Psi-Gly-Psi. These differences indicate that APD may not bind syndecan-2 with the typical binding mode of other PDZ domain proteins. In NMR titration experiments, APD do not bind with the C-terminal TKEFYA peptide of syndecan-2, but can interact with the 32-residue cytoplasmic domain of syndecan-2 very weakly.
Protein and Peptide Letters 02/2009; 16(2):189-95. · 1.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Transport protein particle (TRAPP) is a large multiprotein complex that involves in ER-to-Golgi and intra-Golgi traffic. Synbindin, the human ortholog of yeast Trs23, is one component of the TRAPP complexes. In the hippocampal neurons the synbindin/syndecan complex is involved in synaptic membrane trafficking and thereby regulates the formation of dendritic spines. Here we present the three-dimensional structure of human synbindin, which contains a longin domain (LD) and an atypical PDZ domain (APD). In the crystal, synbindin forms a hexamer, in which the LD forms two different conformations and the APD is quite disordered. These conformational changes of synbindin suggest a possible interaction mode of the LD.
Biochemical and Biophysical Research Communications 06/2008; 378(3):338-43. · 2.41 Impact Factor