https://www.cell.com/cell/pdf/0092-8674(79)90150-8.pdf

The induction of gene activity in drosophila by heat shock

This review gives a comprehensive account of the molecular toxicology of the bicyclic peptides obtained from the poisonous mushrooms of the genus Amanita. The discussion of the biochemical events will be preceded by a consideration of the chemistry of the toxic peptides. The structural features essential for biological activities of both the amatoxins and the phallotoxins will be discussed, also including the most important analytical data. Similar consideration will be given to antamanide, a cyclic peptide, which counteracts phalloidin. In addition, the phallolysins, three cytolytic proteins from Amanita phalloides will be discussed. The report on the biological activity of the amatoxins will deal with the sensitivity of the different RNA-polymerases towards the toxins and with their action on various cell types. Consideration will also be given to systems in which alpha-amanitin was used and can be used as a molecular tool; in the past, many investigators used the inhibitor in molecular biology, genetics, and even in physiological research. As for the phallotoxins, discussion of the affinity of these toxins for actin is provied. Further discussion attempts to understand the course of intoxication by filling in the gap between the first molecular event, formation of microfilaments, and the various lesions in hepatocytes during the intoxication.

Amatoxins, phallotoxins, phallolysin, and antamanide: the biologically active components of poisonous Amanita mushrooms.

This review will attempt to cover the present information on the multiple forms of eukaryotic DNA-dependent RNA polymerases, both at the structural and functional level. Nuclear RNA polymerases constitute a group of three large multimeric enzymes, each with a different and complex subunit structure and distinct specificity. The review will include a detailed description of their molecular structure. The current approaches to elucidate subunit function via chemical modification, phosphorylation, enzyme reconstitution, immunological studies, and mutant analysis will be described. In vitro reconstituted systems are available for the accurate transcription of cloned genes coding for rRNA, tRNA, 5 SRNA, and mRNA. These systems will be described with special attention to the cellular factors required for specific transcription. A section on future prospects will address questions concerning the significance of the complex subunit structure of the nuclear enzymes; the organization and regulation of the gene coding for RNA polymerase subunits; the obtention of mutants affected at the level of factors, or RNA polymerases; the mechanism of template recognition by factors and RNA polymerase.

Eukaryotic RNA polymerases.

A subpopulation of the largest subunit of RNA polymerase II (Pol II LS) is located in 20-50 discrete subnuclear domains that are closely linked to speckle domains, which store splicing proteins. The speckle-associated fraction of Pol II LS is hyperphosphorylated on the COOH-terminal domain (CTD), and it is highly resistant to extraction by detergents. A diffuse nucleoplasmic fraction of Pol II LS is relatively hypophosphorylated on the CTD, and it is easily extracted by detergents. In transcriptionally active nuclei, speckle bound hyperphosphorylated Pol II LS molecules are distributed in irregularly shaped speckle domains, which appear to be interconnected via a reticular network. When transcription is inhibited, hyperphosphorylated Pol II LS and splicing protein SC35 accumulate in speckle domains, which are transformed into enlarged, dot-like structures lacking interconnections. When cells are released from transcriptional inhibition, Pol IIO and SC35 redistribute back to the interconnected speckle pattern of transcriptionally active cells. The redistribution of Pol II and SC35 is synchronous, reversible, and temperature dependent. It is concluded that: (a) hyperphosphorylation of Pol II LS's CTD is a better indicator of its tight association to discrete subnuclear domains than its transcriptional activity; (b) during states of transcriptional inhibition, hyperphosphorylated Pol II LS can be stored in enlarged speckle domains, which under the light microscope appear to coincide with the storage sites for splicing proteins; and (c) Pol II and splicing proteins redistribute simultaneously according to the overall transcriptional activity of the nucleus.

https://rupress.org/jcb/article-pdf/129/2/287/1258834/287.pdf

Transcription-dependent redistribution of the large subunit of RNA polymerase II to discrete nuclear domains.

Messenger RNA synthesis in mammalian cells is catalyzed by the phosphorylated form of RNA polymerase II.

Monoclonal antibodies were raised against purified RNA polymerase II ( or B) from Drosophila melanogaster. The antibody produced by one hybridoma cell clone was found to be directed against the two large subunits of the enzyme. The absence of antibodies directed against proteins possibly contaminating the antigens used for immunization allowed us to identify RNA polymerase unequivocally in interbands and puffs of polytene chromosomes. Within a single heat shock puff (87C1) RNA polymerase was found to be clustered in two separate areas suggesting two distinct regions of RNA polymerase activity in this puff.

Monoclonal antibody directed against RNA polymerase II of Drosophila melanogaster

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2876%2980932-5

In vitro proteolysis of a large subunit of Drosophila melanogaster RNA polymerase B

Using indirect immunofluorescence visualisation techniques we investigated the in situ distribution of RNA polymerase B and histone H1 on the transcriptionally inactive chromatin of salivary gland polytene chromosomes and metaphase chromosomes of Drosophila melanogaster. Transcriptionally inactive chromatin shows no significant staining with antibodies raised against polymerase B, but bright staining with antibodies against histone H1. The lack of staining with antibodies against RNA polymerase B does not appear to be due to inaccessibility of the enzyme to the antibodies; therefore we conclude that transcriptionally inactive chromatin does not contain RNA polymerase B.

Regina Haars

Papers

Monoclonal antibody directed against RNA polymerase II of Drosophila melanogaster

In vitro proteolysis of a large subunit of Drosophila melanogaster RNA polymerase B

Correlation of RNA polymerase B and transcriptional activity in the chromosomes of Drosophila melanogaster

Pro - and Eukaryotic RNA Polymerases