Kinetic Analysis of 3′–5′ Nucleotide Addition Catalyzed by Eukaryotic tRNAHis Guanylyltransferase
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چکیده
منابع مشابه
tRNAHis-guanylyltransferase establishes tRNAHis identity
Histidine transfer RNA (tRNA) is unique among tRNA species as it carries an additional nucleotide at its 5' terminus. This unusual G(-1) residue is the major tRNA(His) identity element, and essential for recognition by the cognate histidyl-tRNA synthetase to allow efficient His-tRNA(His) formation. In many organisms G(-1) is added post-transcriptionally as part of the tRNA maturation process. t...
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All nucleotide polymerases and transferases catalyze nucleotide addition in a 5' to 3' direction. In contrast, tRNA(His) guanylyltransferase (Thg1) enzymes catalyze the unusual reverse addition (3' to 5') of nucleotides to polynucleotide substrates. In eukaryotes, Thg1 enzymes use the 3'-5' addition activity to add G-1 to the 5'-end of tRNA(His), a modification required for efficient aminoacyla...
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GTP:RNA guanylyltransferase catalyzes the initial reaction in the formation of “caps” at 5’ termini of mRNAs. The characteristics of the guanylation reaction have been studied using purified enzyme isolated from vaccinia virus. Guanylation requires a divalent cation (Mg2’), is stimulated by monovalent cations (Na+ and K+), and is unaffected by S-adenosylmethionine. The enzyme utilizes GTP as gu...
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The tRNA(His) guanylyltransferase (Thg1) family comprises a set of unique 3'-5' nucleotide addition enzymes found ubiquitously in Eukaryotes, where they function in the critical G(-1) addition reaction required for tRNA(His) maturation. However, in most Bacteria and Archaea, G(-1) is genomically encoded; thus post-transcriptional addition of G(-1) to tRNA(His) is not necessarily required. The p...
متن کاملNovel non-templated nucleotide addition reactions catalyzed by procaryotic and eucaryotic DNA polymerases.
DNA polymerases catalyze the addition of deoxyribonucleotides onto DNA primers in a template-directed manner. The requirement for template instruction distinguishes these enzymes from other nucleotidyl transferases, such as terminal deoxynucleotidyl transferase, that do not utilize a template. An oligonucleotide substrate was used to characterize a novel, non-templated nucleotide addition react...
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ژورنال
عنوان ژورنال: Biochemistry
سال: 2011
ISSN: 0006-2960,1520-4995
DOI: 10.1021/bi201397f