Specific regions of the polypeptide sequence of pancreatic ribonuclease have been altered by chemical modification and by limited proteolytic digestion in attempts to implicate specific covalent portions of the molecule in the structure and stabilization of the active center. Digestion of the native molecule with trypsin at elevated temperatures has been shown to remove portions of the chain wi...

The circular dichroism spectra of pancreatic ribonuclease A, RNase S, and RNase S-protein have been measured in the wave length interval 198 to 300 mp under various conditions. The circular dichroism spectra of RNase A and S are very similar, possibly identical, over this entire wave length interval at neutral pH. That of RNase S-protein is substantially different. It is shown that the portion ...

2-5A-dependent RNase is the terminal factor in the interferon-regulated 2-5A system thought to function in both the molecular mechanism of interferon action and in the general control of RNA stability. However, direct evidence for specific functions of 2-5A-dependent RNase has been generally lacking. Therefore, we developed a strategy to block the 2-5A system using a truncated form of 2-5A-depe...

Activity of various natural and synthetic polynucleotides as a carrier for streptolysin S was tested in a resting cell system. As the carrier, intact molecules of MS2 RNA, E coli tRNA or rat liver RNA were almost inactive, whereas RNase I core of these RNAs, especially the core fractions eluted from DEAE-cellulose column at higher NaCl concentrations, effectively induced production of the extra...

DNA repair mechanisms are essential for preservation of genome integrity. However, it is not clear how DNA are selected and processed at broken ends by exonucleases during repair pathways. Here we show that the DnaQ-like exonuclease RNase T is critical for Escherichia coli resistance to various DNA-damaging agents and UV radiation. RNase T specifically trims the 3' end of structured DNA, includ...

The nucleoid of Escherichia coli comprises DNA, nucleoid associated proteins (NAPs) and RNA, whose role is unclear. We found that lysing bacterial cells embedded in agarose plugs in the presence of RNases caused massive fragmentation of the chromosomal DNA. This RNase-induced chromosomal fragmentation (RiCF) was completely dependent on the presence of RNase around lysing cells, while the maxima...

Human ribonuclease-1 (hRNase-1) is an extracellular enzyme found in exocrine pancreas, blood, milk, saliva, urine and seminal plasma, which has been implicated in digestion of dietary RNA and in antiviral host defense. The enzyme is characterized by a high catalytic activity toward both single-stranded and double-stranded RNA. In this study, we explored the possibility that hRNase-1 may also be...

The double strand-specific endoRNase RNase III globally regulates the production of antibiotics by Streptomyces coelicolor. We have undertaken studies to determine whether the endoRNase activity of S. coelicolor RNase III or its RNA binding activity is responsible for its regulatory function. We show that an rnc null mutant of S. coelicolor M145 does not produce actinorhodin or undecylprodigios...

RNase P is the ribonucleoprotein enzyme that cleaves precursor sequences from the 5' ends of pre-tRNAs. In Bacteria, the RNA subunit is the catalytic moiety. Eucaryal and archaeal RNase P activities copurify with RNAs, which have not been shown to be catalytic. We report here the analysis of the RNase P RNA from the thermoacidophilic archaeon Sulfolobus acidocaldarius. The holoenzyme was highly...