Biomaterial Database

Partial release of AcPhe-Phe-tRNA from ribosomes during poly(U)-dependent poly(Phe) synthesis and the effects of chloramphenicol. 1990

H J Rheinberger, and K H Nierhaus

Max-Planck-Institut für Molekulare Genetik, Abteilung Wittmann, Berlin-Dahlem, Federal Republic of Germany.

Poly(U)-programmed 70S ribosomes can be shown to be 80% to 100% active in binding the peptidyl-tRNA analogue AcPhe-tRNA to their A or P sites, respectively. Despite this fact, only a fraction of such ribosomes primed with AcPhe-tRNA participate in poly(U)-directed poly(Phe) synthesis (up to 65%) at 14 mM Mg2+ and 160 mM NH4+. Here it is demonstrated that the apparently 'inactive' ribosomes (greater than or equal to 35%) are able to participate in peptide-bond formation, but lose their nascent peptidyl-tRNA at the stage of Ac(Phe)n-tRNA, with n greater than or equal to 2. The relative loss of early peptidyl-tRNAs is largely independent of the degree of initial saturation with AcPhe-tRNA and is observed in a poly(A) system as well. This observation resolves a current controversy concerning the active fraction of ribosomes. The loss of Ac(Phe)n-tRNA is reduced but still significant if more physiological conditions for Ac(Phe)n synthesis are applied (3 mM Mg2+, 150 mM NH4+, 2 mM spermidine, 0.05 mM spermine). Chloramphenicol (0.1 mM) blocks the puromycin reaction with AcPhe-tRNA as expected but, surprisingly, does not affect the puromycin reaction with Ac(Phe)2-tRNA nor peptide bond formation between AcPhe-tRNA and Phe-tRNA. The drug facilitates the release of Ac(Phe)2-4-tRNA from ribosomes at 14 mM Mg2+ while it hardly affects the overall synthesis of poly(Phe) or poly(Lys).

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010452	Peptide Biosynthesis	The production of PEPTIDES or PROTEINS by the constituents of a living organism. The biosynthesis of proteins on RIBOSOMES following an RNA template is termed translation (TRANSLATION, GENETIC). There are other, non-ribosomal peptide biosynthesis (PEPTIDE BIOSYNTHESIS, NUCLEIC ACID-INDEPENDENT) mechanisms carried out by PEPTIDE SYNTHASES and PEPTIDYLTRANSFERASES. Further modifications of peptide chains yield functional peptide and protein molecules.	Biosynthesis, Peptide
D010455	Peptides	Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are considered to be larger versions of peptides that can form into complex structures such as ENZYMES and RECEPTORS.	Peptide,Polypeptide,Polypeptides
D011072	Poly U	A group of uridine ribonucleotides in which the phosphate residues of each uridine ribonucleotide act as bridges in forming diester linkages between the ribose moieties.	Polyuridylic Acids,Uracil Polynucleotides,Poly(rU),Acids, Polyuridylic,Polynucleotides, Uracil
D011691	Puromycin	A cinnamamido ADENOSINE found in STREPTOMYCES alboniger. It inhibits protein synthesis by binding to RNA. It is an antineoplastic and antitrypanosomal agent and is used in research as an inhibitor of protein synthesis.	CL-13900,P-638,Puromycin Dihydrochloride,Puromycin Hydrochloride,Stylomycin,CL 13900,CL13900,P 638,P638
D002701	Chloramphenicol	An antibiotic first isolated from cultures of Streptomyces venequelae in 1947 but now produced synthetically. It has a relatively simple structure and was the first broad-spectrum antibiotic to be discovered. It acts by interfering with bacterial protein synthesis and is mainly bacteriostatic. (From Martindale, The Extra Pharmacopoeia, 29th ed, p106)	Cloranfenicol,Kloramfenikol,Levomycetin,Amphenicol,Amphenicols,Chlornitromycin,Chlorocid,Chloromycetin,Detreomycin,Ophthochlor,Syntomycin
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D012270	Ribosomes	Multicomponent ribonucleoprotein structures found in the CYTOPLASM of all cells, and in MITOCHONDRIA, and PLASTIDS. They function in PROTEIN BIOSYNTHESIS via GENETIC TRANSLATION.	Ribosome
D012346	RNA, Transfer, Amino Acyl	Intermediates in protein biosynthesis. The compounds are formed from amino acids, ATP and transfer RNA, a reaction catalyzed by aminoacyl tRNA synthetase. They are key compounds in the genetic translation process.	Amino Acyl tRNA,Transfer RNA, Amino Acyl,tRNA-Amino Acyl,Amino Acyl T RNA,Acyl tRNA, Amino,Acyl, tRNA-Amino,tRNA Amino Acyl,tRNA, Amino Acyl