Assembly And Function Of Macromolecular Complexes For Accurate Trna Aminoacylation In Helicobacter Pylori
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ASSEMBLY AND FUNCTION OF MACROMOLECULAR COMPLEXES FORACCURATE TRNA AMINOACYLATION IN HELICOBACTER PYLORIbyGAYATHRI SILVAMay 2014Advisor: Dr. Tamara L. HendricksonMajor: Chemistry (Biochemistry)Degree: Doctor of PhilosophyThe aminoacylation of tRNA is a critical step in maintaining the accuracyof the genetic code. Many microorganisms are missing one or more aminoacyltRNA synthetases (aaRSs) and rely on indirect pathways to produce certain aa-tRNAs. In Helicobacter pylori (H. pylori), the genes encoding both asparaginyl tRNA synthetase (AsnRS) and glutaminyl-tRNA synthetase (GlnRS) are missingand the organism consequently relies on the indirect pathway for the synthesis ofAsn-tRNA and Gln-tRNA. The first step of indirect synthesis of Asn-tRNAinvolves misacylation of tRNA by non-discriminating aspartyl tRNA synthetase(ND-AspRS) to produce Asp-tRNA. Next, the misacylated tRNA is converted toAsn-tRNA by Asp-tRNA/Glu-tRNA amidotransferase (Asp/Glu-AdT) toproduce Asn-tRNA. Gln-tRNA is produced vial an analogous process,relying on a misacylating glutamyl-tRNA synthetase, GluRS2 and AdT.Including H. pylori, organisms that indirectly synthesize Asn-tRNA andGln-tRNA require a mechanism for the efficient delivery of both misacylatedtRNAs from the two misacylating enzymes to the amidotransferase enzyme. This
منابع مشابه
Gln-tRNAGln synthesis in a dynamic transamidosome from Helicobacter pylori, where GluRS2 hydrolyzes excess Glu-tRNAGln
In many bacteria and archaea, an ancestral pathway is used where asparagine and glutamine are formed from their acidic precursors while covalently linked to tRNA(Asn) and tRNA(Gln), respectively. Stable complexes formed by the enzymes of these indirect tRNA aminoacylation pathways are found in several thermophilic organisms, and are called transamidosomes. We describe here a transamidosome form...
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