title: Molecular basis for dimer formation of TRbeta variant D355R.
abstract: Protein quality and stability are critical during protein purification for X-ray crystallography. A target protein that is easy to manipulate and crystallize becomes a valuable product useful for high-throughput crystallography for drug design and discovery. In this work, a single surface mutation, D355R, was shown to be crucial for converting the modestly stable monomeric ligand binding domain of the human thyroid hormone receptor (TR LBD) into a stable dimer. The structure of D335R TR LBD mutant was solved using X-ray crystallography and refined to 2.2 A resolution with R(free)/R values of 24.5/21.7. The crystal asymmetric unit reveals the TR dimer with two molecules of the hormone-bound LBD related by twofold symmetry. The ionic interface between the two LBDs comprises residues within loop H10-H11 and loop H6-H7 as well as the C-terminal halves of helices 8 of both protomers. Direct intermolecular contacts formed between the introduced residue Arg 355 of one TR molecule and Glu 324 of the second molecule become a part of the extended dimerization interface of 1330 A(2) characteristic for a strong complex assembly that is additionally strengthened by buffer solutes.
authors.affiliation: Department of Biochemistry and Biophysics, University of California San Francisco (UCSF), San Francisco, California 94158, USA. njouravel@msg.ucsf.edu
authors.forename: Natalia
authors.initials: N
authors.lastname: Jouravel
authors.forename: Elena
authors.initials: E
authors.lastname: Sablin
authors.forename: Marie
authors.initials: M
authors.lastname: Togashi
authors.forename: John D
authors.initials: JD
authors.lastname: Baxter
authors.forename: Paul
authors.initials: P
authors.lastname: Webb
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Fletterick
mesh_terms: D018360:Crystallography, X-Ray; D006801:Humans; D008024:Ligands; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D055550:Protein Stability; D011988:Receptors, Thyroid Hormone / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D008024:Ligands; D050505:Mutant Proteins; D011988:Receptors, Thyroid Hormone
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