Expression of interferon-inducible recombinant human RNase L causes RNA degradation and inhibition of cell growth in Escherichia coli.
Interferon-inducible ribonuclease L (RNase L) is a unique ankyrin-repeat containing endoribonuclease activated by 2',5'-oligoadenylate (2-5A) cofactor leading to RNA degradation and apoptosis during antiviral response in mammalian cells. We report that expression of recombinant human RNase L (1-741 a.a.) caused RNA degradation and inhibition of cell growth in Escherichia coli in absence of exogenous 2-5A. On the contrary, expression of a homologous but dominant negative form of murine RNase L (1-656 a.a.), lacking the RNA binding and ribonuclease domain, did not show RNA degradation, rather it stimulated cell growth. Upon computational analysis by pBLAST search, a putative transcription factor (yahD, F64758, and NP_414852) from the E. coli genome showed highest homology (E value=1e(-17)) with 90-259 a.a. region of human RNase L due to ankyrin repeats with conserved GKT motifs. Ankyrin repeats 6-9 of RNase L are involved in 2-5A binding, dimerization, and activation of the ribonuclease. Thus, a biochemically active human RNase L in E. coli strongly suggests for a prokaryotic cell growth-inhibitory mechanism possibly through ankyrin-ankyrin interaction of YahD and RNase L leading to RNA degradation. The mammalian interferon-inducible RNase L and E. coli yahD protein may have common origin for the ankyrin repeats with 2-5A binding sites. Thus, RNA degradation and cell growth inhibition by recombinant human RNase L biochemically reconstituted mammalian cellular response to interferon in E. coli. RNase L has prokaryotic evolutionary history, it is not only an antiviral but also an antibacterial gene.
Pandey
Mitali
M
Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
Rath
Pramod C
PC
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology; D003067:Coenzymes / Q000378:metabolism; D004722:Endoribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006131:Growth Inhibitors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D012313:RNA / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis; D013045:Species Specificity
D002352:Carrier Proteins; D003067:Coenzymes; D006131:Growth Inhibitors; D011994:Recombinant Proteins; D012313:RNA; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease