In vitro protein synthesis and aging in Rhizoctania solani.
A study was made of the ability of cell-free protein synthesis systems from vegetative cells of different age of the fungus Rhizoctonia solani to produce polyphenylalanine. Polyuridylic acid-directed phenylalanine incorporation into peptides decreased linearly with cell age. The 105,000 x g supernatant fluid and ribosomal fractions were equally responsible for the total loss of synthetic activity of the older cells. Initial rates of phenylalanyl-transfer ribonucleic acid (tRNA) synthetase activity decreased with increasing cell age, which accounted for the defect of the supernatant fraction. An accelerated degradation of soluble phenylalanyl-RNA was associated with the ribosomes of the older cells. In vitro systems from cells of different age transferred phenylalanine from phenylalanyl-tRNA to polyphenylalanine at similar rates. Of the 15 specific aminoacyl-tRNA synthetases assayed, 5 increased and 5 decreased in specific activity with increased age; 3 others did not change during aging and 2 were below acceptable detectable levels.
D000375:Aging; D000596:Amino Acids / Q000378:metabolism; D002247:Carbon Isotopes; D002474:Cell-Free System; D005658:Fungi / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D008025:Ligases / Q000378:metabolism; D010452:Peptide Biosynthesis; D010649:Phenylalanine / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism
D000596:Amino Acids; D002247:Carbon Isotopes; D010649:Phenylalanine; D008025:Ligases