Non-naturally occurring tRNA.sup.Sec and methods of using them for recombinant expression of proteins engineered to include one or more selenocysteine residues are disclosed. The non-naturally occurring tRNA.sup.Sec can be used for recombinant manufacture of selenocysteine containing polypeptides encoded by mRNA without the requirement of an SECIS element. In some embodiments, selenocysteine containing polypeptides are manufactured by co-expressing a non-naturally occurring tRNA.sup.Sec a recombinant expression system, such as E. coli, with SerRS, EF-Tu, SelA, or PSTK and SepSecS, and an mRNA with at least one codon that recognizes the anticodon of the non-naturally occurring tRNA.sup.Sec.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
This invention was made with government support under Agreement Nos. GM022854 awarded-by the National Institutes of Health, DE-FG02-98ER20311 awarded the Department of Energy and 0950474 awarded by the National Science Foundation. The government has certain rights in the invention.