Abstract: The present invention generally relates to various nucleases and uses thereof, and in some cases, to the UPF0054 protein superfamily. Members of the UPF0054 protein superfamily, such as the E. coli protein YbeY, may possess RNase activity and may be involved in certain important cellular processes. Disruption of YbeY activity can lead to increased sensitivity to antibiotics. Accordingly, certain embodiments of the invention are directed to systems and methods for screening target compounds for activity against UPF0054 superfamily proteins. In some embodiments, the screening method allows to target compositions to be determined that show selective activity against UPF0054 superfamily proteins. Other embodiments of the invention provide for nucleases capable of site-specific cleavage of nucleic acids.

Abstract: The present invention provides techniques and reagents for read-through of stop codons in mammalian cells. In certain embodiments, the invention provides methods in which a mammalian cell is contacted with a synthesized tRNA so that the tRNA is taken up into the cell at levels that allow read-through of stop codons. Preferably, the synthesized suppressor tRNA is aminoacylated, optionally with an unnatural amino acid. In certain preferred embodiments, the inventive system is utilized to generate proteins containing two or more unnatural amino acids.

Abstract: The present invention provides techniques and reagents for read-through of stop codons in mammalian cells. In certain embodiments, the invention provides methods in which a mammalian cell is contacted with a synthesized tRNA so that the tRNA is taken up into the cell at levels that allow read-through of stop codons. Preferably, the synthesized suppressor tRNA is aminoacylated, optionally with an unnatural amino acid. In certain preferred embodiments, the inventive system is utilized to generate proteins containing two or more unnatural amino acids.

Abstract: A method of overproducing proteins which are initiated with an amino acid other than methionine, in which methionyl-tRNA transformylase and, optionally, the appropriate tRNA synthetase are overexpressed in a host cell.

Abstract: A method of suppressing a nonsense codon in a gene in a mammalian cell by preparing an oligonucleotide primer having a mismatched anticodon region corresponding to the nonsense codon; preparing a DNA template for production of a tRNA molecule enabling the insertion of an amino acid when the nonsense codon is translated; forming a suppressor gene from said template and primer by site specific mutagenesis; and transforming the suppressor gene into the cell.