RNA decay and maturation have in recent years been recognised as major regulatory mechanisms in bacteria. In contrast to Escherichia coli, the Firmicute (Gram-positive) bacteria often do not encode the well-studied endonuclease RNase E, but instead rely on the endonucleases RNase Y, RNase J1 and RNase J2, of which the latter two have additionally been shown to have 5' to 3' exonucleolytic activ...

Aeropyrum pernix contains one homolog of ribonuclease H (RNase H), A. pernix RNase HII (Ape-RNase HII). Activity characterization showed that Ape-RNase HII exhibited the highest activity in the presence of 5 mM Mn(2+), 1 mM Co(2+), or 10 mM Mg(2+), respectively; however, its cleavage efficiencies at different cleavage sites for Mn(2+) and Mg(2+) were different. Ape-RNase HII cleaved 12-bp RNA/D...

The RNase II superfamily is a ubiquitous family of exoribonucleases that are essential for RNA metabolism. RNase II and RNase R degrade RNA in the 3'-->5' direction in a processive and sequence-independent manner. However, although RNase R is capable of degrading highly structured RNAs, the RNase II activity is impaired by the presence of secondary structures. RNase II and RNase R share structu...

The ribonuclease P (RNase P) in the hyperthermophilic archaeon Pyrococcus horikoshii comprises RNA (PhopRNA) and five proteins. We analyzed the RNA binding mode of the protein, using a pair of complementary fluorescence-labeled oligoribonucleotides. Fluorescence resonance energy transfer (FRET)-based assays suggested that the RNase P proteins assist PhopRNA in attaining a functionally active co...

The regulation of ppp(A2'p)nA-(2-5A)-dependent RNase (RNase L or RNase F) was investigated in NIH 3T3, clone 1 cells using 2-5A-binding and nuclease activity assays. Minimal levels of 2-5A-dependent RNase were detected in actively dividing clone 1 cells; these levels were independently induced by growth arrest or interferon treatment. Accordingly, levels of the RNase were enhanced during growth...

Many flowering plants exhibit an important intraspecific reproductive barrier phenomenon, that is, self-incompatibility (SI), in which S-RNase genes play a significant role. To clarify the specific function of S-RNase genes in Chinese pears, the full length cDNA of PbS 26 -RNase was isolated by rapid amplification of cDNA ends (RACE) technology from Chinese white pear (Pyrus bretschneideri) cul...

Retroviral RNases H are similar in sequence and structure to Escherichia coli RNase HI and yet have differences in substrate specificities, metal ion requirements, and specific activities. Separation of reverse transcriptase (RT) into polymerase and RNase H domains yields an active RNase H from murine leukemia virus (MuLV) but an inactive human immunodeficiency virus (HIV) RNase H. The "handle ...

In order to facilitate studies of the assembly and transport of the site-specific RNase mitochondrial RNA processing (MRP) ribonucleoprotein, we have characterized it from Xenopus laevis cells. X. laevis RNase MRP displayed a similar spectrum of cleavage activity to that produced by previously isolated mammalian nuclear enzymes. A 277-nucleotide RNA component of the ribonucleoprotein was identi...

We demonstrate here for the first time that proline tRNA 3' end maturation in Escherichia coli employs a one-step endonucleolytic pathway that does not involve any of the six 3' → 5' exonucleases (RNase T, RNase PH, RNase D, RNase BN, RNase II and polynucleotide phosphorylase [PNPase]) to generate the mature CCA terminus. Rather, RNase E is primarily responsible for the endonucleolytic removal ...