Analysis of the roles of mutations in thyroid hormone receptor-β by a bacterial biosensor system

• Published in: Journal of molecular endocrinology Vol. 52; no. 1; pp. 55 - 66
• Main Authors: Shi, Changhua, Meng, Qing, Wood, David W
• Format: Journal Article
• Language: English
• Published: England Bioscientifica Ltd 01.02.2014
• Subjects: Amino Acid Substitution; Bacteria - genetics; Bacteria - metabolism; Biosensing Techniques; Humans; Ligands; Models, Molecular; Mutation; Protein Conformation; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Thyroid Hormone Receptors beta - agonists; Thyroid Hormone Receptors beta - antagonists & inhibitors; Thyroid Hormone Receptors beta - chemistry; Thyroid Hormone Receptors beta - genetics; Thyroid Hormone Receptors beta - metabolism; engineered biosensor; hormone receptor mutations; thyroid hormone receptor; ligand-binding assay
• ISSN: 0952-5041; 1479-6813
• DOI: 10.1530/JME-13-0108

Mutations in thyroid hormone receptors (TRs) often lead to metabolic and developmental disorders, but patients with these mutations are difficult to treat with existing thyromimetic drugs. In this study, we analyzed six clinically observed mutations in the ligand-binding domain of the human TRβ using an engineered bacterial hormone biosensor. Six agonist compounds, including triiodothyronine (T3), thyroxine (T4), 3,5,3′-triiodothyroacetic acid (Triac), GC-1, KB-141, and CO-23, and the antagonist NH-3 were examined for their ability to bind to each of the TRβ mutants. The results indicate that some mutations lead to the loss of ability to bind to native ligands, ranging from several fold to several hundred fold, while other mutations completely abolish the ability to bind to any ligand. Notably, the effect of each ligand on each TRβ mutant in this bacterial system is highly dependent on both the mutation and the ligand; some ligands were bound well by a wide variety of mutants, while other ligands lost their affinity for all but the WT receptor. This study demonstrates the ability of our bacterial system to differentiate agonist compounds from antagonist compounds and shows that one of the TRβ mutations leads to an unexpected increase in antagonist ability relative to other mutations. These results indicate that this bacterial sensor can be used to rapidly determine ligand-binding ability and character for clinically relevant TRβ mutants.