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Biomedical subjects

W Sauerbier

Publications and source records attributed to W Sauerbier.

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

A radiological analysis of the transcription units for heterogeneous nuclear RNA in cultured murine cells.

Ultraviolet irradiation of cultured murine cells damages chromosomal DNA, thus causing premature termination of synthesis of hnRNA chains. We have utilized this effect for measuring the sizes of transcription units for the various classes of hnRNA. Target size analyses of the loss of synthesis of hnRNA species suggest that hnRNA, through its entire size range, constitutes mostly primary transcripts-that is, the shorter RNA molecules are not processed from longer precursors. Polyadenylated hnRNA appears to be a primary transcript as well. Our data, however, are also consistent with processing of precursors to poly(A)+ hnRNA from the 5'termini of larger hnRNA molecules. They are not consistent with models which postulate that poly(A)+ hnRNA sequences originate at the 3' termini of precursors which are considerably larger (greater than 30%) than the polyadenylated hnRNA molecules themselves. Finally, we have found that the process of polyadenylation is not measurably affected by ultraviolet irradiation of cells.

Cell Line↗
PubMed1976

End group of naturally terminated and UV lesion terminated T7 in vitro RNA.

The 3' terminal nucleosides of RNA transcribed in vitro by E. coli RNA polymerase from T7 DNA and UV irradiated TN DNA were determined. The 3' terminal nucleoside of naturally terminated (t1 termination site) RNA cytidine. In the case of RNA terminated at UV lesions, it is cytidine in 0 per cent of the molecules and adenosine in the remaining 30 per cent. Cytidine trialcohols are labile in high concentrations of KOH and at high temperature and appear to convert to uridine.

Adenosine↗
PubMed1976

Utilization of early promotors in mutant far P85 of bacteriophage T4.

We show that farP85 is a recessive mutant of T4 incapable of activating the delayed early promotors for genes 43 and 45 and that the farP85 mutation is in the same complementation group as the ts G1 mutation, which is located in the "modifier of transcription" (mot) gene.

Coliphages↗
PubMed1974

Transcription unit mapping in bacteriophage T7. II. Proportionality of number of gene copies, mRNA, and gene product.

The effect of UV irradiation of bacteriophage T7 on in vivo early RNA synthesis has been studied by direct quantitation of the gene-specific RNA transcripts. The results show that the early region of phage T7 is transcribed from left to right as a single unit. Furthermore, gene inactivation, the UV sensitivity of synthesis of gene-specific RNA, and the UV sensitivity of synthesis of the corresponding proteins all follow pseudo first-order kinetics in multiply infected cells, demonstrating a random statistical correlation between both transcriptional sampling of gene copies and translational sampling of the resultant RNA transcripts. In addition, these simple kinetics imply an absence of positive feedback mechanisms compensating for the differential decline of individual early gene products in cells multiply infected with phage T7.

Coliphages↗
PubMed1974

Two modes of in vivo transcription for genes 43 and 45 of phage T4.

Sensitivities of the expression of early genes of phage T4 to UV light were determined at various stages of intracellular development of T4 wild type, a DNA-negative mutant (T4 DO), and T4 tsG1, (a mutant that exhibits delayed expression of some T4 early genes). Whereas the sensitivities of some genes in the T4 wild type and T4 DO remain constant, genes 43 and 45 exhibit greatly reduced sensitivities several minutes after the onset of phage development. Since UV sensitivities are a measure of the distance of a gene from its promotor, these observations indicate a switch from distal, "immediate early" promotors to proximal, "delayed early" promotors for genes 43 and 45. In the tsG1 mutant this decrease in UV sensitivities of genes 43 and 45 does not occur at 42 C, suggesting that at high temperature this mutant does not utilize the delayed early promotors.

Amino Acids↗
PubMed1973

Control of gene function in bacteriophage T4. IV. Post-transcriptional shutoff of expression of early genes.

The selective and sequential shutoff of synthesis of early T4 proteins in bacteria infected with DNA-negative mutants is under the active control of one or more T4-induced proteins. Selective shutoff of synthesis of early T4 proteins is accompanied by a selective degradation of distinct species of T4 mRNA. We present circumstantial evidence that selective degradation of mRNA is the cause, and not the consequence, of selective termination of expression of early T4 genes. The mutation sp62 inactivates the shutoff mechanism and prevents the selective degradation of distinct species of T4 mRNA.

Amino Acids↗
PubMed1973

Transcription units in bacteriophage T4.

We have investigated the possibility of assigning genes of T4 bacteriophage to their units of transcription (scriptons) by studying gene expression from UV-irradiated DNA templates. Since RNA chains are prematurely terminated on UV-irradiated DNA templates and since the promotor distal part of the RNA chain is deleted, the expression of any gene is inversely proportional to the distance between the promotor and the promotor distal end of the gene. We find that the early genes, 43, 45 and rIIB, are promotor proximal. Since at least genes 43 and rIIB are classified as delayed early genes, these results suggest that their synthesis may require the recognition of new promotors. Additional early genes (44, 62, 42, 46, 47, 55, and rIIA) and some late genes (34, 37, and 38) have also been assigned positions relative to their promotors.

Coliphages↗
PubMed1973

Transcription unit mapping in bacteriophage T7. I. In vivo transcription by Escherichia coli RNA polymerase.

Premature termination of transcription at UV lesions in DNA permits a study of the sequential order of transcription by E. coli RNA polymerase of the genes in the early region of T7. This analysis is extended to the transcription by E. coli polymerase of the late region of T7 by deleting the early terminator. The results demonstrate the existence of a single large transcription unit spanning the early region, with a promotor located at the left end of the T7 genome. Furthermore, there are no initiation sites for E. coli RNA polymerase in the late region. When E. coli polymerase transcribes the late region, it does so exclusively by initiation at the early promotor.

Amino Acids↗
PubMed1971

Control of gene function in bacteriophage Tr. 3. Preventing the shutoff of early enzyme synthesis.

Synthesis of early T4 protein, which is normally shut off at 10 min after infection, continues until lysis when host cells have been preinfected with T3 sam(+). In host cells preinfected with T3 sam(-), synthesis of early enzymes is shut off as normal. Thus, S-adenosylmethionine is required for the turnoff of early T4 functions (at least when host cells have been preinfected with T3).

Aminohydrolases↗