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The structure of human thyroglobulin

DOI: 10.1038/s41586-020-1995-4 DOI Help

Authors: Francesca Coscia (MRC Laboratory of Molecular Biology) , Ajda Taler-verčič (Jožef Stefan Institute; Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins, Slovenia) , Veronica T. Chang (MRC Laboratory of Molecular Biology) , Ludwig Sinn (Technische Universität Berlin) , Francis J. O'reilly (Technische Universität Berlin) , Thierry Izore (MRC Laboratory of Molecular Biology) , Miha Renko (Jožef Stefan Institute) , Imre Berger (University of Bristol) , Juri Rappsilber (Technische Universität Berlin; University of Edinburgh) , Dušan Turk (Jožef Stefan Institute; Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins, Slovenia) , Jan Lowe (MRC Laboratory of Molecular Biology)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature , VOL 37

State: Published (Approved)
Published: February 2020
Diamond Proposal Number(s): 17434

Abstract: Thyroglobulin (TG) is the protein precursor of thyroid hormones, which are essential for growth, development and the control of metabolism in vertebrates. Hormone synthesis from TG occurs in the thyroid gland via the iodination and coupling of pairs of tyrosines, and is completed by TG proteolysis3. Tyrosine proximity within TG is thought to enable the coupling reaction but hormonogenic tyrosines have not been clearly identified, and the lack of a three-dimensional structure of TG has prevented mechanistic understanding4. Here we present the structure of full-length human thyroglobulin at a resolution of approximately 3.5 Å, determined by cryo-electron microscopy. We identified all of the hormonogenic tyrosine pairs in the structure, and verified them using site-directed mutagenesis and in vitro hormone-production assays using human TG expressed in HEK293T cells. Our analysis revealed that the proximity, flexibility and solvent exposure of the tyrosines are the key characteristics of hormonogenic sites. We transferred the reaction sites from TG to an engineered tyrosine donor–acceptor pair in the unrelated bacterial maltose-binding protein (MBP), which yielded hormone production with an efficiency comparable to that of TG. Our study provides a framework to further understand the production and regulation of thyroid hormones.

Journal Keywords: Cryoelectron microscopy; Endocrine system and metabolic diseases; Enzyme mechanisms

Subject Areas: Biology and Bio-materials

Diamond Offline Facilities: Electron Bio-Imaging Centre (eBIC)
Instruments: Krios III-Titan Krios III at Diamond

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