title: Exploiting the 21st amino acid-purifying and labeling proteins by selenolate targeting.
abstract: Selenium is essential to human life and occurs in selenoproteins as selenocysteine (Sec), the 21st amino acid. The selenium atom endows selenocysteine with unique biochemical properties, including a low pK(a) and a high reactivity with many electrophilic agents. Here we describe the introduction of selenocysteine into recombinant non-selenoproteins produced in Escherichia coli, as part of a small tetrapeptide motif at the C terminus. This selenocysteine-containing motif could subsequently be used as a protein tag for purification of the recombinant protein, selenolate-targeted labeling with fluorescent compounds or radiolabeling with either gamma-emitting (75)Se or short-lived positron emitters such as (11)C. The results presented here thus show how a wide range of biotechnological applications can be developed starting from the insertion of selenocysteine into proteins.
authors.affiliation: Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, SE-171 77 Stockholm, Sweden.
authors.forename: Linda
authors.initials: L
authors.lastname: Johansson
authors.forename: Chunying
authors.initials: C
authors.lastname: Chen
authors.forename: Jan-Olov
authors.initials: JO
authors.lastname: Thorell
authors.forename: Anna
authors.initials: A
authors.lastname: Fredriksson
authors.forename: Sharon
authors.initials: S
authors.lastname: Stone-Elander
authors.forename: Guro
authors.initials: G
authors.lastname: Gafvelin
authors.forename: Elias S J
authors.initials: ES
authors.lastname: Arnér
mesh_terms: D003001:Cloning, Molecular / Q000379:methods; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D015202:Protein Engineering / Q000379:methods*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D017279:Selenocysteine / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D013194:Staining and Labeling / Q000379:methods
chemical_list: D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; D017279:Selenocysteine