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H F Noller

Publications and source records attributed to H F Noller.

157 records · Page 9Linked to original sources
PubMed1975

Identification of a ribosomal protein essential for peptidyl transferase activity.

Extraction with 2 M lithium chloride removes a group of proteins (LiC1 SP) from 50S ribosomal subunits. Both the LiC1 SP and the resulting cores, which contain the remaining proteins as well as 5S and 23S RNA, lack peptidyl transferase activity, as measured by the "fragment reaction". Activity can be restored to the LiC1 cores by reconstitution with LiC1 SP under conditions of high temperature and high ionic strength. The LiC1 SP proteins were fractionated by carboxymethyl-cellulose and Sephadex G-100, and the individual fractions were tested by this reconstitution system. Of the 18 ribosomal proteins found in the LiC1 SP, only L16 is essential for reconstitution of peptidyl transferase activity.

Acyltransferases↗
PubMed1972

Functional modification of 16S ribosomal RNA by kethoxal.

Kethoxal reacts with 30S ribosomal subunits to give totally inactive particles, as measured by in vitro protein synthesis. It is postulated that functional modification occurs at the binding site for transfer RNA since (a) loss of specific binding of transfer RNA, but not binding of messenger RNA, is simultaneous with loss of protein synthesis, and (b) loss of activity is inhibited by bound transfer RNA. By means of in vitro reconstitution and labeling techniques, it is found that loss of transfer RNA-binding activity is correlated with the modification of six or seven guanine residues in 16S RNA.

Aldehydes↗
PubMedDate not supplied

Interaction of antibiotics with functional sites in 16S ribosomal RNA.

Chemical footprinting shows that several classes of antibiotics (streptomycin, tetracycline, spectinomycin, edeine, hygromycin and the neomycins) protect concise sets of highly conserved nucleotides in 16S ribosomal RNA when bound to ribosomes. These findings have strong implications for the mechanism of action of these antibiotics and for the assignment of functions to specific structural features of 16S rRNA.

Aminoglycosides↗
PubMedDate not supplied

Structure and function of ribosomal RNA.

A refined model has been developed for the folding of 16S rRNA in the 30S subunit, based on additional constraints obtained from new experimental approaches. One set of constraints comes from hydroxyl radical footprinting of each of the individual 30S ribosomal proteins, using free Fe(2+)-EDTA complex. A second approach uses localized hydroxyl radical cleavage from a single Fe2+ tethered to unique positions on the surface of single proteins in the 30S subunit. This has been carried out for one position on the surface of protein S4, two on S17, and three on S5. Nucleotides in 16S rRNA that are essential for P-site tRNA binding were identified by a modification interference strategy. Ribosomal subunits were partially inactivated by chemical modification at a low level. Active, partially modified subunits were separated from inactive ones by binding 3'-biotinderivatized tRNA to the 30S subunits and captured with streptavidin beads. Essential bases are those that are unmodified in the active population but modified in the total population. The four essential bases, G926, 2mG966, G1338, and G1401 are a subset of those that are protected from modification by P-site tRNA. They are all located in the cleft of our 30S subunit model. The rRNA neighborhood of the acceptor end of tRNA was probed by hydroxyl radical probing from Fe2+ tethered to the 5' end of tRNA via an EDTA linker. Cleavage was detected in domains IV, V, and VI of 23S rRNA, but not in 5S or 16S rRNA. The sites were all found to be near bases that were protected from modification by the CCA end of tRNA in earlier experiments, except for a set of E-site cleavages in domain IV and a set of A-site cleavages in the alpha-sarcin loop of domain VI. In vitro genetics was used to demonstrate a base-pairing interaction between tRNA and 23S rRNA. Mutations were introduced at positions C74 and C75 of tRNA and positions 2252 and 2253 of 23S rRNA. Interaction of the CCA end of tRNA with mutant ribosomes was tested using chemical probing in conjunction with allele-specific primer extension. The interaction occurred only when there was a Watson-Crick pairing relationship between positions 74 of tRNA and 2252 of 23S rRNA. Using a novel chimeric in vitro reconstitution method, it was shown that the peptidyl transferase reaction depends on this same Watson-Crick base pair.

Models, Biological↗