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D P Nierlich

Publications and source records attributed to D P Nierlich.

At least 37 records · Page 2Linked to original sources
PubMed1976

Ribosomal subunit entry into polysomes in yeast.

The kinetics of entry of newly synthesized 40 S and 60 S ribosomal subunits into yeast polysomes is described. The entry times for 40 S and 60 S subunits were found to be 3 and 8 min, respectively. The kinetics of entry of 40 S subunits into large polysomes is found to be different from the kinetics of entry of 60 S subunits into large polysomes.

Adenine↗
PubMed1975

Regulation of RNA synthesis in Escherichia coli during a shift-up transition.

These experiments investigate two aspects of RNA synthesis in Escherichia coli ML30 during the transition from a relatively slow rate of growth to a more rapid one: (1) the number of growing RNA molecules per cell, and (2) the average time required for addition of a nucleotide onto a growing RNA chain. Cells were grown at 30 degrees C in a glucose-minimal salts medium and shifted-up by the addition of Casamino acids. Measurements were made of the rates of incorporation over short intervals (e.g. 5,8,12, and 16 s) of [3-H]guanine into the internal and 3'-terminal nucleotides of RNA. After correction for the specific activities of the intracellular GTP pools, and for the rate of [3-H]guanine accumulation at the 3'-terminus of non-growing RNA, the rates of chain elongation were calculated. It was found that cells growing at a rate of 0.9 generations/h contain approx. 4800 RNA molecules, growing at a rate of 28 nucleotides/s per chain. Cells growing exponentially at the postshift-up rate (1.2 generations/h) contain 7000 RNA molecules per unit equivalent cell mass, which are growing at a rate of 32 nucleotides/s per molecule. Three min after shift-up, cells contain the same number or slightly fewer (10%) growing RNA molecules than cells prior to shift-up, 4300, and these are being elongated at a rate of about 32 nucleotides per s. The results are consistent with the view that in the range of growth rates studied, the total rate of RNA synthesis is regulated through a limitation in the number of functioning RNA polymerase molecules, each working at a relatively constant, presumably maximal, average rate.

Cell Division↗
PubMed1975

Cleavage of Nonglucosylated Bacteriophage T4 deoxyribonucleic acid by Restriction Endonuclease Eco RI.

DNAs lacking the glucosyl modification (Glc-) and additionally lacking the 6-methylaminopurine (N6-methyladenine) modification (Glc-, MeAde-) were prepared from appropriate T4 mutants. These DNAs were cleaved by the purified restriction endonuclease Eco TI from Escherichia coli. Normally modified DNA (Glc+, MeAde+) was not attached. The Eco RII and the hemophilus enzymes Hin dII and Hin dIII do not attack Glc-, MeAde- T DNA, possibly due to the presence of 6-hydroxymethylcytosine. Eco RI produces approximately 40 specific fragments from Glc- DNA ranging in molecular weights from 0.3 to 10.5 X 10-6.

Adenine↗
PubMed1975

Initiation and transcription of a set of transfer ribonucleic acid genes in vitro.

Using RNA polymerase purified from Escherichia coli, DNA isolated from the bacteriophage T4, and a bacterial supernatant fraction containing the necessary processing enzymes, a set of transfer RNAs can be formed in vitro. To characterize the site or sites of initiation of this tRNA transcription, rifampicin-resistant complexes of RNA polymerase, DNA, and either ATP (UTP and CTP) or GTP (UTP and CTP) were formed, and tRNA was transcribed from these stabilized sites. It is concluded that transcription of the entire set is initiated by ATP. To study the transcription of the tRNAs, the time sequence of the appearance of individual species was determined during synchronous transcription of a preformed RNA polymerase-DNA complex. The appearance of three RNA species is found to be consistent with the sequential transcription of a large polycistronic cluster; the order and distances, inferred from the times of transcription, are as required by the existing gene map. It is concluded that the initiation of tRNA transcription can occur, without accessory factors, with the insertion of ATP at a single or a few closely spaced sites, and that the tRNAs encoded by the bacteriophage T4 are present in a single operon.

Chromosome Mapping↗
PubMed1974

Regulation of bacterial growth.

Is the control of bacterial metabolism so complex? The answer can be found in a simple experiment. Two cultures of bacteria are grown in different mediums. One contains as the carbon and nitrogen sources a mixture of amino acids, while the other contains only glucose and ammonia, so that the cells must synthesize all of the amino acids. The results show that insofar as the cells in both cultures grow at comparable rates, they will have the same composition in terms of DNA, RNA, and protein (30). To explain this phenomena I have argued that through the control mechanisms responsible for the distribution of substrates in intermediary metabolism, the substrates of protein synthesis are produced at concentrations and rates commensurate with the ability of the environment to support growth. The provision of these substrates relative to the ability of the protein forming system to utilize them regulates the synthesis of ribosomal and transfer RNA, which, after adjustment for various modulating influences, such as nonfunctioning ribosomes or ribosomal RNA turnover, brings the number of functioning ribosomes to a point in keeping with the provision of external nutrients. The synthesis of messenger (or total) RNA, ribosomal proteins, and DNA, and the process of cell division, for example, are subject to their own controls, but through the burden they each place on intermediary metabolism, they provide a means for partitioning the cell's metabolic resources. It might be noted that this view may not be very far from the idea once held that the rate at which each of the transfer RNA's was changed by amino acids regulate the synthesis of bacterial RNA, but growth regulation is clearly more complicated than implied by that model (76).

Adenine Nucleotides↗
PubMed1973

Transfer RNA synthesis in vitro.

During infection of Escherichia coli, bacteriophage T4 directs the synthesis of at least eight transfer RNAs and of two stable RNA species of low molecular weight, of unknown function. When T4 DNA is incubated with purified RNA polymerase and the appropriate substrates, a high molecular weight RNA is produced. This RNA, on further incubation with a supernatant fraction prepared from E. coli, is cleaved to several species of RNA. These cleaved RNAs were analyzed by gel electrophoresis and fingerprint techniques, and were found to be similar or identical to those made in vivo. The fingerprint analysis of one of these, a tRNA(Gly), is presented. The molecule made in vitro, except for the absence of modified bases, appears to be identical to the RNA made by T4-infected cells. Therefore, in this system the tRNA genes are transcribed with fidelity, the transcript is cleaved correctly, and the tRNAs are made in good yield.

Base Sequence↗