The 2-5A system contributes to the antiviral effect of interferons through the synthesis of 2-5A and its activation of the ribonuclease, RNase L. RNase L degrades viral and cellular RNA after activation by unique, 2'-5' phosphodiester-linked, oligoadenylates [2-5A, (pp)p5' A2'(P5'A2')]n, n >=2. Because both the 2-5A system and apoptosis can serve as viral defense mechanisms and RNA degradation ...

The introduction of non-natural amino acid residues or modules into proteins provides a new means to explore the basis for conformational stability, folding/unfolding behavior, or biological function. We exploited intein-mediated protein ligation to produce a semisynthetic ribonuclease A. Of the 124 residues of RNase A, residues 1-94 were linked to an intein. After expression of the fusion prot...

While identifying genes regulated by ribonuclease III (RNase III) in Escherichia coli, we observed that steady-state levels of betT mRNA, which encodes a transporter mediating the influx of choline, are dependent on cellular concentrations of RNase III. In the present study, we also observed that steady-state levels of betT mRNA are dependent on RNase III activity upon exposure to osmotic stres...

Escherichia coli RNase E, an essential single-stranded specific endoribonuclease, is required for both ribosomal RNA processing and the rapid degradation of mRNA. The availability of the complete sequences of a number of bacterial genomes prompted us to assess the evolutionarily conservation of bacterial RNase E. We show here that the sequence of the N-terminal endoribonucleolytic domain of RNa...

A mutant of ribonuclease T1 (RNase T1), denoted RNase Talpha, that is designed to recognize double-stranded ribonucleic acid was created. RNase Talpha carries the structure of RNase T1 except for a part of its loop L3 domain, which has been swapped for a corresponding domain from alpha-sarcin. The RNase Talpha maintains the pleated beta-sheet structure and retains the guanyl-specific ribonuclea...

Type I IFNs were discovered as the primary antiviral cytokines and are now known to serve critical functions in host defense against bacterial pathogens. Accordingly, established mediators of IFN antiviral activity may mediate previously unrecognized antibacterial functions. RNase-L is the terminal component of an RNA decay pathway that is an important mediator of IFN-induced antiviral activity...

Ribonuclease L (RNase L) is a metal-ion-independent endoribonuclease associated with antiviral and antibacterial defense, cancer and lifespan. Despite the biological significance of RNase L, the RNAs cleaved by this enzyme are poorly defined. In this study, we used deep sequencing methods to reveal the frequency and location of RNase L cleavage sites within host and viral RNAs. To make cDNA lib...

The control of mRNA stability is an important component of regulation in bacteria. Processing and degradation of mRNAs are initiated by an endonucleolytic attack, and the cleavage products are processively degraded by exoribonucleases. In many bacteria, these RNases, as well as RNA helicases and other proteins, are organized in a protein complex called the RNA degradosome. In Escherichia coli, ...

The RNase H family of enzymes degrades RNA in RNA.DNA hybrids in a divalent cation-dependent manner. RNases H from diverse sources such as Escherichia coli and human immunodeficiency virus (HIV) share homologous metal-binding active sites, and the activity of the RNase H domain of reverse transcriptase (RT) is required for retroviral replication. The isolated RNase H domain from HIV RT, however...

Ribonuclease P (RNase P) is an essential endonuclease that catalyzes the 5' end maturation of precursor tRNA (pre-tRNA). Bacterial RNase P is an attractive potential antibacterial target because it is essential for cell survival and has a distinct subunit composition compared to the eukaryal counterparts. To accelerate both structure-function studies and discovery of inhibitors of RNase P, we d...