AUTHOR=Wright David E. , Siddika Tarana , Heinemann Ilka U. , O’Donoghue Patrick 

TITLE=Delivery of the selenoprotein thioredoxin reductase 1 to mammalian cells

JOURNAL=Frontiers in Molecular Biosciences

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/molecular-biosciences/articles/10.3389/fmolb.2022.1031756

DOI=10.3389/fmolb.2022.1031756

ISSN=2296-889X

ABSTRACT=<p>Over-expression of genetically encoded thioredoxin reductase 1 (TrxR1) TrxR1 can be toxic to cells due to the formation of a truncated version of the enzyme. We developed a new mammalian cell-based model to investigate TrxR1 activity. Fusion of the HIV-derived cell penetrating peptide (TAT) enabled efficient cellular uptake of purified TrxR1 containing 21 genetically encoded amino acids, including selenocysteine. The TAT peptide did not significantly alter the catalytic activity of TrxR1 <italic>in vitro</italic>. We monitored TrxR1-dependent redox activity in human cells using a TrxR1-specific red fluorescent live-cell reporter. Using programmed selenocysteine incorporation in <italic>Escherichia coli</italic>, our approach allowed efficient production of active recombinant human selenoprotein TrxR1 for delivery to the homologous context of the mammalian cell. The delivered TAT-TrxR1 showed robust activity in live cells and provided a novel platform to study TrxR1 biology in human cells.</p>