Selenocysteine Insertion at a Predefined UAG Codon in a Release Factor 1 (RF1)-depleted Escherichia coli Host Strain Bypasses Species Barriers in Recombinant Selenoprotein Translation
Year: 2017
Type: article
Abstract: Selenoproteins contain the amino acid selenocysteine (Sec), co-translationally inserted at a predefined UGA opal codon by means of Sec-specific translation machineries. In Escherichia coli , this process is dependent upon binding of the Sec-dedicated elongation factor SelB to a Sec insertion sequence (SECIS) element in the selenoprotein-encoding mRNA and competes with UGA-directed translational termination. Here, we found that Sec can also be efficiently incorporated at a predefined UAG amber codon, thereby competing with RF1 rather than RF2. Subsequently, utilizing the RF1-depleted E. coli strain C321.ΔA, we could produce mammalian selenoprotein thioredoxin reductases with unsurpassed purity and yield. We also found that a SECIS element was no longer absolutely required in such a system. Human glutathione peroxidase 1 could thereby also be produced, and we could confirm a previously proposed catalytic tetrad in this selenoprotein. We believe that the versatility of this new UAG-directed production methodology should enable many further studies of diverse selenoproteins.
Source: Journal of Biological Chemistry
Authors: Qing Cheng, Elias S.J. Arnér
Institution: Karolinska Institutet
Language: English
Subfield: Nutrition and Dietetics
Field: Nursing
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W2589024705