Decay of pre-existing ribonucleic acid was studied in Escherichia coli cells subjected to high temperature or to starvation for nitrogen, phosphate, amino acids, or a carbon source. In these studies, a series of mutants affected in ribonuclease I (RNase I, EC 3.1.4.22) polynucleotide phosphorylase (EC 2.7.7.8) or ribonuclease II (RNase II, EC 3.1.4.23) were used. Degradation of total RNA and th...

PROTEIN ENGINEERING TO EXPLOIT AND EXPLORE -----BOV~~EeR~~~~ELEAS~~~S====~==~~~---Jin-Soo Kim Under the supervision of Dr. Ronald T. Raines at the University of Wisconsin-Madison Ribonuclease 5-peptide (residues 1-20) and 5-protein (residues 21124) are the enzymatically inactive products of the limited digestion of bovine pancreatic ribonuclease A (RNase A) by subtilisin. 5-Peptide binds 5-prot...

RNA editing adds and deletes uridine nucleotides in many preedited mRNAs to create translatable mRNAs in the mitochondria of the parasite Trypanosoma brucei. Kinetoplastid RNA editing protein B3 (KREPB3, formerly TbMP61) is part of the multiprotein complex that catalyzes editing in T. brucei and contains an RNase III motif that suggests nuclease function. Repression of KREPB3 expression, either...

The secondary structures of the eubacterial RNase P RNAs are being elucidated by a phylogenetic comparative approach. Sequences of genes encoding RNase P RNA from each of the recognized subgroups (alpha, beta, gamma, and delta) of the proteobacteria have now been determined. These sequences allow the refinement, to nearly the base pair level, of the phylogenetic model for RNase P RNA secondary ...

Ribonuclease A (RNase A) and the ribonuclease inhibitor protein (RI) form one of the tightest known protein-protein complexes. RNase A variants and homologues, such as G88R RNase A, that retain ribonucleolytic activity in the presence of RI are toxic to cancer cells. Herein, a new and facile assay is described for measuring the equilibrium dissociation constant (K(d)) and dissociation rate cons...

Cytotoxic ribonucleases with antitumor activity are mainly found in the oocytes and early embryos of frogs, and share sequence similarity with each other. They all belong to the RNase A superfamily but possess different cytotoxicities, base specificities and ribonucleolytic activities. RC-RNase 4, one of the five novel ribonucleases isolated from the oocytes of Rana catesbeiana, is a 106 amino ...

Host defense against invading pathogens is of great importance to the survival of higher organisms. We have been studying the evolution of mammalian eosinophil-associated ribonucleases (EARs), which are members of the ribonuclease A superfamily with known antipathogen activities. Earlier studies showed that positive selection promoted rapid diversification of paralogous EAR genes in both primat...

Disulfide bonds play important roles in the folding and stability of proteins and are evolutionarily conserved. A classic example is RNase A (also known as bovine pancreatic ribonuclease), which contains 4 conserved disulfide bonds among 8 cysteines. However, human RNase 8, a paralog of RNase A uniquely expressed in the placenta, has lost one of the conserved cysteines but gained another, when ...