Functional Expression of Thyroid-Stimulating Hormone Receptor on Nano-Sized Bacterial Magnetic Particles in Magnetospirillum magneticum AMB-1

Abstract

The measurement of autoantibodies to thyroid-stimulating hormone receptor (TSHR) is important for the diagnosis of autoimmune thyroid disease such as Graves’ disease (GD). Although TSHR from porcine thyroid membrane is commonly used for the measurement of TSHR autoantibodies (TRAb), recombinant human TSHR (hTSHR) remains ideal in terms of stable supply and species identity. Here we set out to express recombinant hTSHR on the lipid-bilayer surface of magnetic nanoparticles from a magnetotactic bacterium, Magnetospirillum magneticum AMB-1. Using a tetracycline-inducible expression system, we successfully overexpressed functional hTSHR on bacterial magnetic particles (BacMPs) in AMB-1 via an anchor protein specific for BacMPs. The overexpressed hTSHR was membrane integrated and possessed both ligand and autoantibody binding activity. Our data suggest that hTSHR-displayed BacMPs have potential as novel tools for ligand-receptor interaction analysis or for TRAb immunoassay in GD patients.

Functional Expression of Full-Length TrkA in the Prokaryotic Host Magnetospirillum magneticum AMB-1 by Using a Magnetosome Display System

“…The amount of Mms13-TrkA fusion protein on the magnetosomes was calculated as 106 ng/mg of magnetosomes based on the calibration curve. This value was comparable to that of the thyroid-stimulating hormone receptor and Mms13 fusion protein (17.2 ng/mg of magnetosome) that has been used for autoantibody detection (19). These results indicate that a sufficient amount of TrkA on magnetosomes was successfully produced for the ligand-binding assay.…”

“…Target proteins can be efficiently expressed on magnetosomes using Mms13 as a fusion partner (16). The system for target protein expression on magnetosomes using Mms13, which we call the magnetosome display system, has enabled us to produce a wide range of functional proteins, such as an estrogen receptor, a D1 dopamine receptor, and a thyroid-stimulating hormone receptor (17)(18)(19). These receptors are major targets for drug discovery, some of which were not successfully expressed in E. coli because of cytotoxic effects.…”

Bioengineered Polyhydroxyalkanoates as Immobilized Enzyme Scaffolds for Industrial Applications

“…Interestingly, magnetosomes can be functionalized in vivo by fusing foreign proteins of interest to the magnetosome membrane proteins, such as MamC/Mms13, MagA, and Mms16 (Arakaki et al, 2008;Ren et al, 2018). The translational fusion of functional proteins to these transmembrane proteins of magnetosomes has led to numerous successful prototypes in a wide range of applications, including of industrial uses (Ginet et al, 2011;Sugamata et al, 2013;Honda et al, 2015a,b;Xiang et al, 2017;Mickoleit and Schüler, 2018). The inherent magnetic characteristics of magnetosomes make them very useful in some situations, especially for implementation in magneticfield-related technologies, such as magneto-immunoassays and biomedical imaging (Ren et al, 2018).…”

Magnetotactic bacteria: nanodrivers of the future

“…Sugamata (2013) expressed recombinant hTSHR on the lipid-bilayer surface of magnetosomes using a tetracyclineinducible expression system. Further, it was suggested that hTSHR-displayed magnetosomes had potential for ligandreceptor interaction analysis in GD patients.…”