title: Isolation and characterization of Streptomyces aureofaciens protein-synthesis elongation factor Tu in an aggregated state.
abstract: The ability of EF-Tu to aggregate spontaneously was employed for the purification of homogeneous EF-Tu . GDP from Streptomyces aureofaciens. The formation of filamentous structures in the aggregated EF-Tu was demonstrated in a light microscope. The purified factor, with a specific activity of 19,100 +/- 1,000 units/mg in [3H]GDP exchange, was shown to be active in the translation of poly(U). Aggregated EF-Tu . GDP exhibited almost eight-times lower GDP-exchange capacity at 2 degrees C than at 30 degrees C. This suggests that GDP-binding sites are not freely accessible at lower temperatures in the aggregated factor, in contrast to Escherichia coli polymerized EF-Tu. Turbidimetric assays revealed that the solubilization of diluted aggregated S. aureofaciens EF-Tu is strongly dependent on temperature and causes an increase in the number of accessible GDP-binding sites.
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis*; D001665:Binding Sites; D006153:Guanosine Diphosphate / Q000302:isolation & purification; D010444:Peptide Elongation Factor Tu; D010445:Peptide Elongation Factors / Q000302:isolation & purification*; D012995:Solubility; D013304:Streptomyces aureofaciens / Q000378:metabolism* / Q000648:ultrastructure; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D010445:Peptide Elongation Factors; D006153:Guanosine Diphosphate; D010444:Peptide Elongation Factor Tu