In eukaryotes, ribonuclease P (RNase P) requires both RNA and protein components for catalytic activity. The eukaryotic RNase P RNA, unlike its bacterial counterparts, does not possess intrinsic catalytic activity in the absence of holoenzyme protein components. We have used a sensitive photoreactive cross-linking assay to explore the substrate-binding environment for different eukaryotic RNase...

Pancreatic-type ribonucleases can exert toxic activity by catalyzing the degradation of cellular RNA. Their ability to enter cells is essential for their cytotoxicity. Here, we determine the mechanism by which bovine pancreatic ribonuclease (RNase A) enters human cells. Inhibiting clathrin-dependent endocytosis with dynasore or chlorpromazine decreases RNase A-uptake by ~70%. Limited colocaliza...

The interferon antiviral pathways and prostate cancer genetics converge on a regulated endoribonuclease, RNase L. Positional cloning and linkage studies mapped Hereditary Prostate Cancer 1 (HPC1) to RNASEL. To date, there is no correlation of viral infections with prostate cancer, suggesting that RNase L may play additional roles in tumor suppression. Here, we demonstrate a role of RNase L as a...

The crystal structure of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) bound to an RNA/DNA hybrid reveals an extensive network of contacts with the phosphate backbone of the DNA strand approximately 4-9 bp downstream from the ribonuclease H (RNase H) catalytic center. Collectively designated as 'the RNase H primer grip', this motif contains a phosphate binding pocket an...

Ribonuclease mitochondrial RNA processing (RNase MRP) is a multifunctional ribonucleoprotein (RNP) complex that is involved in the maturation of various types of RNA including ribosomal RNA. RNase MRP consists of a potential catalytic RNA and several protein components, all of which are required for cell viability. We show here that the temperature-sensitive mutant of rmp1, the gene for a uniqu...

RNase MRP is a ribonucleoprotein enzyme involved in processing precursor rRNA in eukaryotes. To facilitate our structure-function analysis of RNase MRP from Saccharomyces cerevisiae, we have determined the likely secondary structure of the RNA component by a phylogenetic approach in which we sequenced all or part of the RNase MRP RNAs from 17 additional species of the Saccharomycetaceae family....

A variant of bovine pancreatic ribonuclease A has been prepared with seven amino acid substitutions (Q55K, N62K, A64T, Y76K, S80R, E111G, N113K). These substitutions recreate in RNase A the basic surface found in bovine seminal RNase, a homologue of pancreatic RNase that diverged some 35 million years ago. Substitution of a portion of this basic surface (positions 55, 62, 64, 111 and 113) enhan...

Escherichia coli contains multiple exoribonucleases. Strains lacking the exoribonucleases RNase II, D, BN, T, and PH are inviable. The introduction of a chromosomal, wild-type copy of the gene for any one of these enzymes is sufficient to allow cell growth, with the enzymes being in the following order of effectiveness: RNase T > RNase PH > RNase D > RNase II > RNase BN. The data indicate that ...

Bovine seminal ribonuclease (BS-RNase), a dimeric homolog of bovine pancreatic ribonuclease A (RNase A), is toxic to mammalian cells. In contrast to dimeric BS-RNase, a monomeric BS-RNase and RNase A are not cytotoxic and are bound tightly by cytosolic ribonuclease inhibitor. To elucidate the mechanism of ribonuclease cytotoxicity, we constructed a series of hybrid and semisynthetic enzymes and...

RNase D was recently reported as a new enzymatic activity associated with HIV-1 reverse transcriptase (RT), cleaving RNA at two positions within the double-stranded region of the tRNA primer-viral RNA template complex (Ben-Artzi et al., Proc. Natl. Acad. Sci. USA 89 (1992) 927-931). This would make RNase D a fourth distinct activity of HIV-1 RT, in addition to RNA- and DNA-dependent DNA polymer...