Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Autoantibodies to aminoacyl-transfer RNA (tRNA) synthetases are common in the human autoimmune diseases polymyositis and dermatomyositis. Sera of the PL-12 specificity contain separate antibodies reacting with alanyl-tRNA synthetase and alanine tRNA (tRNAAla). The antibodies to tRNA recognize at least six distinguishable human tRNAAla species grouped into two sequence families. The antibody-reactive determinants on the tRNA were identified through ribonuclease protection and oligonucleotide binding experiments. The antibody binding site is a seven- to nine-nucleotide sequence containing the anticodon loop and requires an intact anticodon. No requirement for anticodon stem structure or sequence is observed, although the 5' portion of the stem is protected from nuclease attack. Antibodies from several patients appear to share the same specificitym, indicating that the antibodies are induced by a unique sequence feature in the immunogen.
 ...
PMID:Autoreactive epitope defined as the anticodon region of alanine transfer RNA. 244 87

Recent experiments showed that a single base pair (G3:U70) in the amino acid acceptor helix is a major determinant for the identity of Escherichia coli alanine transfer RNA. Experiments reported here show that bound alanine tRNA synthetase protects (from ribonuclease attack) seven consecutive phosphodiester linkages on the 3'-side of the acceptor-T psi C helix (phosphates 65-71) and a few additional sites that are in scattered locations. There is no evidence for interaction of the enzyme with the anticodon, a sequence which can be varied without effect on recognition by alanine tRNA synthetase.
 ...
PMID:Evidence for interaction of an aminoacyl transfer RNA synthetase with a region important for the identity of its cognate transfer RNA. 305 91

Members of the Mycobacterium avium complex (MAC) exhibit a highly effective and biphasic response to starvation, losing less than 90% viability after 2 years in deionized water. During the first adaptive phase of 4-7 days, the bacilli exhibit a burst of lipid catabolism, alteration of mycolate modifications, loss of catalase and urease activities, and a decline in sensitivity to antibiotics. There is also a decline in the protein level of alanine tRNA synthetase (AlaS), and an increase in ribonuclease E (Rne) levels. During the following persistence phase, the bacilli become metabolically dormant. However, with return of nutrients, the cells rapidly respond with increased activity, as determined by reduction of a tetrazolium dye. The primary reservoir for MAC is natural and municipal water, and the metabolic dormancy may be analogous to that of other aquatic organisms, such as vibrio. The organized metabolic shutdown that environmental mycobacteria utilize to survive starvation may have evolved into the host-specific dormancy mechanisms of Mycobacterium tuberculosis.
 ...
PMID:Mycobacterium avium enters a state of metabolic dormancy in response to starvation. 1585 Jul 53

A ribonuclease, with a molecular mass of 9 kDa and an N-terminal sequence resembling the sequence of a fragment of tRNA/rRNA cytosine-C5-methylase and a fragment of a alanyl-tRNA synthetase, was isolated from fresh fruiting bodies of the brown oyster mushroom Pleurotus ostreatus. The ribonuclease was purified using a very simple protocol that comprised ion-exchange chromatography on carboxymethyl (CM)-cellulose and affinity chromatography on Affi-gel blue gel. Subsequent gel filtration by fast protein liquid chromatography on Superdex 75 and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis revealed that the ribonuclease was purified after the first two chromatographic steps. The ribonuclease was adsorbed on CM-cellulose and Affi-gel blue gel. The ribonuclease exhibited the highest activity toward poly A, lower activity toward poly C, slight activity toward poly G, and indiscernible activity toward poly U. The enzyme was stimulated upon exposure to 1 microm Mg2+ and 10 microm Zn2+, but was inhibited by the following ions at 10 mm: Ca2+, Mg2+, Zn2+, Cu2+, Fe2+, Mn2+, and Fe3+. The ribonuclease required a pH of 8.0 and a temperature of 50-70 degrees C to express maximal activity. It had a Km of 60 microm toward yeast tRNA. It lacked mitogenic and HIV-1 reverse transcriptase inhibiting activities, but exerted antiproliferative activity toward leukemia L1210 cells.
 ...
PMID:A low-molecular mass ribonuclease from the brown oyster mushroom. 1594 90

In bacteria, ribosomes stalled at the 3'-end of nonstop or defective mRNAs are rescued by the action of a specialized ribonucleoprotein complex composed of tmRNA and SmpB protein in a process known as trans-translation; for recent reviews see Dulebohn et al. [2007], Keiler [2007], and Moore and Sauer [2007]. tmRNA is a bifunctional RNA that acts as both a tRNA and an mRNA. SmpB-bound tmRNA is charged with alanine by alanyl-tRNA synthetase and recognized by EF-Tu (GTP). The quaternary complex of tmRNA-SmpB-EF-Tu and GTP recognizes stalled ribosomes and transfers the nascent polypeptide to the tRNA-like domain of tmRNA. A specialized reading frame within tmRNA is then engaged as a surrogate mRNA to append a 10 amino acid (ANDENYALAA) tag to the C-terminus of the nascent polypeptide. A stop codon at the end of the tmRNA reading frame then facilitates normal termination and recycling of the translation machinery. Through this surveillance mechanism, stalled ribosomes are rescued, and nascent polypeptides bearing the C-terminal tmRNA-tag are directed for proteolysis. Several proteases (ClpXP, ClpAP, Lon, FtsH, and Tsp) are known to be involved in the degradation of tmRNA-tagged proteins (Choy et al., 2007; Farrell et al., 2005; Gottesman et al., 1998; Herman et al., 1998, 2003; Keiler et al., 1996). In addition to its ribosome rescue and peptide tagging activities, trans-translation also facilitates the selective decay of nonstop mRNAs in a process that is dependent on the activities of SmpB protein, tmRNA, and the 3' to 5'-exonuclease, RNase R (Mehta et al., 2006; Richards et al., 2006; Yamamoto et al., 2003). Here, we describe methods and strategies for the purification of tmRNA, SmpB, Lon, and RNase R from Escherichia coli that are likely to be applicable to other bacterial species. Protocols for the purification of the Clp proteases, Tsp, and FtsH, as well as EF-Tu and other essential E. coli translation factors may be found elsewhere (Joshi et al., 2003; Kihara et al., 1996; Makino et al., 1999; Maurizi et al., 1990; Shotland et al., 2000). In addition, we present biochemical and genetic assays to study the various aspects of the trans-translation mechanism.
 ...
PMID:Studying tmRNA-mediated surveillance and nonstop mRNA decay. 1916 51