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Biomedical subjects

E Kuechler

Publications and source records attributed to E Kuechler.

70 records · Page 4Linked to original sources
PubMed1977

Poly(4-thiouridylic acid) as messenger RNA and its application for photoaffinity labelling of the ribosomal mRNA binding site.

Poly(4-thiouridylic acid) [poly(s4U)] synthesized by polymerization of 4-thiouridine 5'-diphosphate with Escherichia coli polynucleotide phosphorylase (EC 2.7.7.8) acts as messenger RNA in vitro in a protein-synthesizing system from E. coli. It stimulates binding of Phe-tRNA to ribosomes both in the presence of EF-Tu-Ts at 5 mM Mg2+ concentration and nonenzymatically at 20 mM Mg2+ concentration. It codes for the synthesis of polyphenylalanine. Poly(s4U) competes with poly(U) for binding to E. coli ribosomes. Light of 330 nm photoactivates poly(s4U) thus making it a useful photoaffinity label for the ribosomal mRNA binding site. Upon irradiation of 70-S ribosomal complexes, photoreaction occurs with ribosomal proteins as well as 16-S RNA. Ribosomes pre-incubated with R17 RNA are protected against the photoaffinity reaction. The labelling of 16-S RNA can be reduced by treatment of ribosomes with colicin E3.

Affinity Labels↗
PubMed1975

Affinity-labelling of Escherichia coli ribosomes by a derivative of phenylalanyl-tRNA. A critical test for the specificity.

Under nonenzymatic binding conditions p-nitrophenoxycarbonyl-phenylalanyl-tRNA can be bound to the donor as well as the acceptor site on the Escherichia coli ribosome. Precharging ribosomes with phenylalanyl-tRNA in the presence of elongation factor Tu and GTP blocks both the donor- and the acceptor site against affinity labelling by p-nitrophenoxycarbonyl-phenylalanyl-tRNA.

Affinity Labels↗
PubMed1974

Proteins at the tRNA binding sites of Escherichia coli ribosomes.

p - Nitrophenylcarbamyl - phenylalanyl-tRNA binds to ribosomes in response to poly(U) and reacts with ribosomal proteins via covalent bond formation. Ribosomal proteins of Escherichia coli were characterized by two-dimensional gel electrophoresis and by reaction with specific antibodies. The affinity label is shown to react with the 50S proteins L27, L15, L2, L16, and L14. We therefore conclude that these particular proteins are located at or near tRNA-binding sites within the 50S ribosomal subunit.

Animals↗
PubMed1969

Two rapidly labeled RNA species in the polysomes of antibody-producing lymphoid tissue.

Popliteal lymph nodes of rabbits stimulated to produce antibodies were pulse labeled in vivo by direct injection of (3)H-uridine. RNA was then extracted from isolated polysomes and single ribosomes. Fractionation of this RNA by polyacrylamide gel electrophoresis revealed the synthesis of two discrete peaks of labeled RNA migrating in the region between 18S ribosomal and 4S transfer RNA. These peaks were found in the RNA extracted from polysomes but were absent from single ribosomes. When the polysomes were disrupted by EDTA treatment the RNA species no longer appeared as rapidly sedimenting material. These two RNA's have molecular weights near 2.2 x 10(5) and 3.7 x 10(5) daltons. The chemical and biological properties of these species as well as the molecular weights are consistent with those expected for monocistronic messenger RNA coding for the antibody L and H chains, respectively.

Animals↗