Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.8 (polynucleotide phosphorylase)
 723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Poly(4-thiouridylic acid) as messenger RNA and its application for photoaffinity labelling of the ribosomal mRNA binding site. 32 11

Controlled RNA degradation is known to be achieved via the exosome in Eukarya and Archaea, and the RNA degradosome in Bacteria. In this issue of the Biochemical Journal, Taghbalout et al. demonstrate in Escherichia coli that many additional proteins of the RNA degradation and processing network co-localize with the RNA degradosome in supramolecular structures. The latter appear as extended cytoplasmic membrane-associated assemblies that coil around the periphery of the cell when visualized by immunofluorescence microscopy. The co-localizing ensemble of RNA metabolic proteins includes RNaseE, PNPase (polynucleotide phosphorylase), the DEAD-box RNA helicase RhlB, the oligo-RNase Orn, RNases II and III, PAP I [poly(A) polymerase I], RppH (RNA pyrophosphohydrolase), proteins RraA and RraB that are negative regulators of RNaseE, and the RNA chaperone Hfq. Not all cellular RNA-binding proteins associate with these structures, as shown for EF-Tu (elongation factor Tu) and Rho helicase. Formation of the supramolecular architecture was shown to not be dependent on two other known cytoskeletal systems or on RNA de novo synthesis or nucleoid positioning within the cell. This novel dimension of compartmentalization in bacteria that lack classic cell compartments opens new perspectives on how RNA homoeostasis is achieved, organized and regulated in bacteria such as E. coli.
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PMID:Supramolecular membrane-associated assemblies of RNA metabolic proteins in Escherichia coli. 2426 91