Open AccessTermination of Polypeptide Synthesis in Bacteria and the Exchange of Ribosomal Subunits
Author(s) -
Perazzolo Clovis A.,
Azzam Mansur E.,
Algranati Israel D.
Publication year - 1973
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1973.tb02781.x
Subject(s) - polysome , ribosome , monomer , protein biosynthesis , ribosomal rna , protein subunit , chemistry , biochemistry , escherichia coli , spermidine , ribosomal protein , rna , enzyme , organic chemistry , polymer , gene
A cell‐free system able to elongate and terminate nascent peptide chains has been prepared with polyribosomes and supernatant fraction from Escherichia coli D 10 . When labeled 30‐S subunits were added in several conditions and at different moments, the exchange of radioactivity between 70‐S and 30‐S particles could be measured during and after termination of protein synthesis. The subunit exchange taking place during completion of polypeptide synthesis was not modified by the presence of spermidine, used to stabilize 70‐S ribosomes. This result led to the conclusion that upon termination and release of polypeptide chains, ribosomes dissociate and detach from polysomes as 30‐S and 50‐S subparticles. The “hybrid” 70‐S monomer formed after the exchange with added 30‐S subunits, behaves as a run‐off ribosome.