The selenocysteine toolbox: A guide to studying the 21st amino acid

Chung, Christina Z.; Krahn, Natalie

doi:10.1016/j.abb.2022.109421

Cited by 14 publications

(14 citation statements)

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“…This situation has contributed to the rapid development of various techniques for expressing proteins containing selenocysteine, including mammalian, bacterial, and cell-free systems. A recent paper reviews these techniques [ 12 ]. The attention attracted by selenoproteins has also led to the rapid development of methods for the synthesis of selenopeptides, including solid-phase peptide synthesis (SPPS) and native chemical ligation.…”

Section: Introductionmentioning

confidence: 99%

Selenium in Peptide Chemistry

et al. 2023

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In recent years, researchers have been exploring the potential of incorporating selenium into peptides, as this element possesses unique properties that can enhance the reactivity of these compounds. Selenium is a non-metallic element that has a similar electronic configuration to sulfur. However, due to its larger atomic size and lower electronegativity, it is more nucleophilic than sulfur. This property makes selenium more reactive toward electrophiles. One of the most significant differences between selenium and sulfur is the dissociation of the Se-H bond. The Se-H bond is more easily dissociated than the S-H bond, leading to higher acidity of selenocysteine (Sec) compared to cysteine (Cys). This difference in acidity can be exploited to selectively modify the reactivity of peptides containing Sec. Furthermore, Se-H bonds in selenium-containing peptides are more susceptible to oxidation than their sulfur analogs. This property can be used to selectively modify the peptides by introducing new functional groups, such as disulfide bonds, which are important for protein folding and stability. These unique properties of selenium-containing peptides have found numerous applications in the field of chemical biology. For instance, selenium-containing peptides have been used in native chemical ligation (NCL). In addition, the reactivity of Sec can be harnessed to create cyclic and stapled peptides. Other chemical modifications, such as oxidation, reduction, and photochemical reactions, have also been applied to selenium-containing peptides to create novel molecules with unique biological properties.

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Section: Introductionmentioning

confidence: 99%

Selenium in Peptide Chemistry

et al. 2023

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“…The complicated translation path of eukaryotic selenoproteins poses a challenge to overexpress and purify these proteins for functional characterization studies. Some strategies [e.g., pSelExpress1, orthogonal aminoacyl-tRNA synthetase (aaRS):tRNA pairs] have been developed to address this challenge in eukaryotes [reviewed in ( Novoselov et al, 2007 ; Chung and Krahn, 2022 )]. However, the bacterial Sec insertion system is simpler, only requiring a specialized elongation factor (SelB) to recognize Sec-tRNA Sec and the SECIS element for insertion of Sec.…”

Section: Introductionmentioning

confidence: 99%

“…However, the bacterial Sec insertion system is simpler, only requiring a specialized elongation factor (SelB) to recognize Sec-tRNA Sec and the SECIS element for insertion of Sec. As a result, more methodologies have been developed for recombinant Sec insertion in bacteria [reviewed in ( Chung and Krahn, 2022 )]. We have specifically focused on engineering SECIS-independent translation by removing the requirement for SelB and instead using the canonical elongation factor (EF-Tu) ( Aldag et al, 2013 ).…”

Section: Introductionmentioning

confidence: 99%

Dual incorporation of non-canonical amino acids enables production of post-translationally modified selenoproteins

Morosky

Comyns

Nunes

et al. 2023

Front. Mol. Biosci.

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Post-translational modifications (PTMs) can occur on almost all amino acids in eukaryotes as a key mechanism for regulating protein function. The ability to study the role of these modifications in various biological processes requires techniques to modify proteins site-specifically. One strategy for this is genetic code expansion (GCE) in bacteria. The low frequency of post-translational modifications in bacteria makes it a preferred host to study whether the presence of a post-translational modification influences a protein’s function. Genetic code expansion employs orthogonal translation systems engineered to incorporate a modified amino acid at a designated protein position. Selenoproteins, proteins containing selenocysteine, are also known to be post-translationally modified. Selenoproteins have essential roles in oxidative stress, immune response, cell maintenance, and skeletal muscle regeneration. Their complicated biosynthesis mechanism has been a hurdle in our understanding of selenoprotein functions. As technologies for selenocysteine insertion have recently improved, we wanted to create a genetic system that would allow the study of post-translational modifications in selenoproteins. By combining genetic code expansion techniques and selenocysteine insertion technologies, we were able to recode stop codons for insertion of Nε-acetyl-l-lysine and selenocysteine, respectively, into multiple proteins. The specificity of these amino acids for their assigned position and the simplicity of reverting the modified amino acid via mutagenesis of the codon sequence demonstrates the capacity of this method to study selenoproteins and the role of their post-translational modifications. Moreover, the evidence that Sec insertion technology can be combined with genetic code expansion tools further expands the chemical biology applications.

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“…9,10 Selenocysteine (SeCys) Selenocysteine is the 21st proteinogenic amino acid and it is encoded by DNA and hence an essential constituent of redoxactive enzymes, such as glutathione peroxidase (GPx) and thioredoxin reductase (TRx). [11][12][13][14][15] SeCys plays important roles in various biological functions including the regulation of thyroid metabolism, cellular redox balance, cancer prevention and immune responses, and is a powerful antioxidant and detoxifier. [16][17][18][19] Therefore, the development of fluorescent probes for real-time monitoring of SeCys in vivo is of utmost interest for understanding the physiological functions of SeCys and even provide clues associated with human diseases owing to inappropriate concentrations of SeCys.…”

Section: Introductionmentioning

confidence: 99%