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Evidence of the involvement of a 50S ribosomal protein in several active sites.
Metadata
Journalbiochemistry2.865Date
1975-Dec-02
Publication Type
Research Support, U.S. Gov't, P.H.S.
Journal Article
Volume
1975-Dec-02 / 14 : 5321-7
Author
Fahnestock SR
DoiPMIDMESH
Binding Sites
Geobacillus stearothermophilus
Hydrogen-Ion Concentration
Kinetics
Macromolecular Substances
Oxidation-Reduction
Photochemistry
Protein Binding
Ribosomal Proteins
Ribosomes
Abstract
The functional role of the Bacillus stearothermophilus 50S ribosomal protein B-L3 (probably homologous to the Escherichia coli protein L2) was examined by chemical modification. The complex [B-L3-23S RNA] was photooxidized in the presence of rose bengal and the modified protein incorporated by reconstitution into 50S ribosomal subunits containing all other unmodified components. Particles containing photooxidized B-L3 are defective in several functional assays, including (1) poly(U)-directed poly(Phe) synthesis, (2) peptidyltransferase activity, (3) ability to associate with a [30S-poly(U)-Phe-tRNA] complex, and (4) binding of elongation factor G and GTP. The rates of loss of the partial functional activities during photooxidation of B-L3 indicate that at least two independent inactivating events are occurring, a faster one, involving oxidation of one or more histidine residues, affecting peptidyltransferase and subunit association activities and a slower one affecting EF-G binding. Therefore the protein B-L3 has one or more histidine residues which are essential for peptidyltransferase and subunit association, and another residue which is essential for EF-G-GTP binding. B-L3 may be the ribosomal peptidyltransferase protein, or a part of the active site, and may contribute functional groups to the other active sites as well.
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2.9
Biochemistrybiochemistry
Metadata
LocationUnited States
FromAMER CHEMICAL SOC

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