Pyrrolysine is incorporated using a dedicated
Pyrrolysine amber suppression requires dedicated orthogonal translation components distinct from canonical termination machinery. Incorporation at in-frame UAG within methylamine methyltransferase genes depends on specialized transfer RNA tRNAPyl bearing CUA anticodon and cognate pyrrolysyl-tRNA synthetase PylRS charging tRNAPyl with pyrrolysine exclusively without interacting with host synthetases. Delivery to ribosome utilizes elongation factor EF-Tu or archaeal EF1A competing with release factor RF1. No release factor or RNA polymerase directly inserts amino acid; only translation apparatus handles recognition. Orthogonal pair transplantation into Escherichia coli and mammalian cells confirms sufficiency of tRNA plus synthetase for UAG recoding, establishing basis for synthetic biology expansion applications.
Ref: NCBI Bookshelf, Synthetic Biology: tRNA and Synthetase for Pyrrolysine Insertion