Biomaterial Database

Evidence for a precursor-product relationship in the biosynthesis of ribosomal protein S20. 1977

G A Mackie

The kinetics of labeling ribosomal protein S20 of Escherichia coli strains H882 and H882 groE44 have been examined using partial reconstitution as a means of binding this and some other 30S subunit proteins selectively to 16S RNA from crude extracts prepared by acetic acid extraction of pulse-labeled whole cells. The rate of labeling of S20 during short pulses at 44 degrees C is less than 20% of that observed at 28 degrees C. S20 can be recovered from the cells labeled at the higher temperature if they are chased at 28 degrees C, but not at 44 degrees C, in the presence of excess sulfate prior to their extraction. These observations suggest that S20 is derived from a precursor whose processing is blocked at 44 degrees C. Among the proteins extracted from cells labeled at 44 degrees C capable of binding to 16S RNA is a novel polypeptide, p2, which is not normally present on the 30S subunit. The kinetics of its appearance at 44 degrees C, and its chasing at 28 degrees C, suggest a precursor-product relationship with S20. p2 contains a tryptic peptide with the chromatographic properties of the peptide Ser-Met-Met-Arg at position 25-28 in S20. A second methionine-containing peptide at positions 49-59 of S20 is missing from p2. In addition, the apparent molecular weight of p2 (8600) is less than that of S20 (9500). p2 may represent the product of degradation of a precursor to S20, yet retains the ability to bind to 16S RNA. It is much less likely that p2 is a bona fide precursor which is converted into S20 by fusion to some other polypeptide.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010446	Peptide Fragments	Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.	Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D002918	Chymotrypsin	A serine endopeptidase secreted by the pancreas as its zymogen, CHYMOTRYPSINOGEN and carried in the pancreatic juice to the duodenum where it is activated by TRYPSIN. It selectively cleaves aromatic amino acids on the carboxyl side.	Alpha-Chymotrypsin Choay,Alphacutanée,Avazyme
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
D012269	Ribosomal Proteins	Proteins found in ribosomes. They are believed to have a catalytic function in reconstituting biologically active ribosomal subunits.	Proteins, Ribosomal,Ribosomal Protein,Protein, Ribosomal
D012335	RNA, Ribosomal	The most abundant form of RNA. Together with proteins, it forms the ribosomes, playing a structural role and also a role in ribosomal binding of mRNA and tRNAs. Individual chains are conventionally designated by their sedimentation coefficients. In eukaryotes, four large chains exist, synthesized in the nucleolus and constituting about 50% of the ribosome. (Dorland, 28th ed)	Ribosomal RNA,15S RNA,RNA, 15S
D013045	Species Specificity	The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.	Species Specificities,Specificities, Species,Specificity, Species
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures
D014176	Protein Biosynthesis	The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.	Genetic Translation,Peptide Biosynthesis, Ribosomal,Protein Translation,Translation, Genetic,Protein Biosynthesis, Ribosomal,Protein Synthesis, Ribosomal,Ribosomal Peptide Biosynthesis,mRNA Translation,Biosynthesis, Protein,Biosynthesis, Ribosomal Peptide,Biosynthesis, Ribosomal Protein,Genetic Translations,Ribosomal Protein Biosynthesis,Ribosomal Protein Synthesis,Synthesis, Ribosomal Protein,Translation, Protein,Translation, mRNA,mRNA Translations