Peroxidase in the presence of hydrogen peroxide catalyzes in vitro the activation of the carcinogenic azo dye Sudan I (1-phenylazo-2-hydroxynaphthalen) to tRNA-, homopolyribonucleotide- and 5'-monophosphate nucleoside-bound products. tRNA, poly G and guanosine 5'-monophosphate modified by activated Sudan I become colored and have an absorption maximum of approx. 480 nm. Cochromatographic analys...

Accumulation of 16S rRNA and production of guanosine polyphosphates (pppGpp and ppGpp) were studied during amino acid starvation in three wild-type strains of Helicobacter pylori. All strains exhibit a relaxed phenotype with respect to accumulation of 16S rRNA. This constitutes the first example of a wild-type eubacterium showing a relaxed phenotype. The guanosine polyphosphate levels do not ri...

The multiprotein mTORC1 protein kinase complex is the central component of a pathway that promotes growth in response to insulin, energy levels, and amino acids and is deregulated in common cancers. We find that the Rag proteins--a family of four related small guanosine triphosphatases (GTPases)--interact with mTORC1 in an amino acid-sensitive manner and are necessary for the activation of the ...

Eukaryotic cells critically depend on the correct regulation of intracellular vesicular trafficking to transport biological material. The Rab subfamily of small guanosine triphosphatases controls these processes by acting as a molecular on/off switch. To fulfill their function, active Rab proteins need to localize to intracellular membranes via posttranslationally attached geranylgeranyl lipids...

Purine nucleosides on position 9 of eukaryal and archaeal tRNAs are frequently modified in vivo by the post-transcriptional addition of a methyl group on their N1 atom. The methyltransferase Trm10 is responsible for this modification in both these domains of life. While certain Trm10 orthologues specifically methylate either guanosine or adenosine at position 9 of tRNA, others have a dual speci...

The 5' end of tobacco mosaic virus (TMV) genomic RNA is capped with 7-methylguanosine. A virus-coded polypeptide with guanylyltransferase activity has been investigated. This enzyme is responsible for forming the 5'----5' linkage of guanosine 5'-monophosphate to the 5'-diphosphate of an acceptor RNA, thereby forming the cap. A critical step in the mechanism for cap formation in the eukaryotic n...

Guanosine diphosphate d-glucose:d-glucose-6-phosphate 1-glucosyl-transferase was purified approximately 100-fold from extracts of Streptomyces hygroscopicus. The purified enzyme catalyzed the transfer of glucose from guanosine diphosphate-d-glucose to glucose-6-phosphate to form trehalose phosphate and guanosine diphosphate. The enzyme was specific for these two substrates and was stimulated by...