Abstract: The invention relates to a biological system for diminishing cell growth or inducing selective killing of target cells, in particular pathogenic bacterial or fungal cells, or cancer cells. The biological system is based on toxin-antitoxin systems, as found in prokaryotic plasmids and their host chromosomes. The biological system comprises a vehicle with a first nucleic acid sequence or amino acid sequence encoding for a prokaryotic toxin of a prokaryotic toxin-antitoxin pair, and a second nucleic acid sequence or amino acid sequence encoding for the corresponding prokaryotic antitoxin of the prokaryotic toxin-antitoxin pair. The system is characterized in that the toxin and/or the antitoxin is operably linked to a protein output modifier (POM) that comprises a nucleic acid sequence or amino acid sequence that modifies the relative rate of transcription, mRNA stability, mRNA translatability or protein stability of the toxin and/or antitoxin.

Abstract: The invention relates to a biological system for diminishing cell growth or inducing selective killing of target cells, in particular pathogenic bacterial or fungal cells, or cancer cells. The biological system is based on toxin-antitoxin systems, as found in prokaryotic plasmids and their host chromosomes. The biological system comprises a vehicle with a first nucleic acid sequence or amino acid sequence encoding for a prokaryotic toxin of a prokaryotic toxin-antitoxin pair, and a second nucleic acid sequence or amino acid sequence encoding for the corresponding prokaryotic antitoxin of the prokaryotic toxin-antitoxin pair. The system is characterized in that the toxin and/or the antitoxin is operably linked to a protein output modifier (POM) that comprises a nucleic acid sequence or amino acid sequence that modifies the relative rate of transcription, mRNA stability, mRNA translatability or protein stability of the toxin and/or antitoxin.

Abstract: The invention relates to a method for engineering a nucleic acid for expression in the presence of Kid/PemK endoribonuclease comprising (i) screening the nucleotide sequence of the nucleic acid for the sequence UUACU or TTACT (ii) mutating said sequence such that there are no longer any occurrences of UUACU or TTACT. The invention also relates to a method of making a ribonucleic acid resistant to Kid/PemK endoribonuclease, said method comprising (a) providing a nucleic acid; (b) screening the nucleic acid for the nucleotide sequence UUACU or TTACT; (c) mutating said sequence such that there are no longer any occurrences of UUACU or TTACT; wherein when the nucleic acid of (a) is a deoxyribonucleic acid, said method further comprises (d) transcribing said deoxyribonucleic acid to produce ribonucleic acid. The invention also relates to vectors and uses of purified or recombinant Kid/PemK endoribonucleases.