3CI9

Crystal Structure of the human HSBP1

Summary for 3CI9

• Entry DOI: 10.2210/pdb3ci9/pdb
• Descriptor: Heat shock factor-binding protein 1 (2 entities in total)
• Functional Keywords: triple helix, nucleus, transcription
• Biological source: Homo sapiens (Human)
• Cellular location: Nucleus: O75506
• Total number of polymer chains: 2
• Total formula weight: 10964.36

Authors

Liu, X.,Xu, L.,Liu, Y.,Zhu, G.,Zhang, X.C.,Li, X.,Rao, Z. (deposition date: 2008-03-11, release date: 2009-01-20, Last modification date: 2024-05-29)

Primary citation

Liu, X.,Xu, L.,Liu, Y.,Tong, X.,Zhu, G.,Zhang, X.C.,Li, X.,Rao, Z.
Crystal structure of the hexamer of human heat shock factor binding protein 1
Proteins, 75:1-11, 2009

PubMed Abstract: Heat shock response (HSR) is a ubiquitous cellular mechanism that copes with a variety of stresses. This response is mediated by a family of transcriptional activators, heat shock factors (HSFs), which are under tight regulation. HSF binding protein 1 (HSBP1) is a negative regulator of HSR and is reported to bind specifically with the active trimeric form of HSF1, thus inhibiting its activity. HSBP1 contains heptad-repeats in the primary sequence and was believed to stay in a trimer form in solution. We report the crystal structure of the trimerization domain of the M30I/L55P mutant of human HSBP1 at 1.8 A resolution. In this crystal form, the HSBP1 fragment of residues 6-53 forms a continuous, 11-turn long helix. The helix self-associates to form a parallel, symmetrical, triple coiled-coil helix bundle, which further assembles into a dimer of trimers in a head-to-head fashion. Solution study confirmed that the wild-type HSBP1 shares similar biophysical properties with the crystallized variant. Furthermore, we identified Ser31, which buried its polar side chain in the hydrophobic interior of the helix bundle, as a stability weak-spot. Substitution of this residue with Ile increases the melting temperature by 24 degrees C, implicating that this conserved serine residue is maintained at position 31 for functional purposes.

PubMed: 18767159
DOI: 10.1002/prot.22216

Experimental method

X-RAY DIFFRACTION (1.8 Å)