We recently described an orthogonal initiator tRNA (itRNATy2) that can initiate protein synthesis with noncanonical amino acids (ncAAs) in response to the UAG nonsense codon. Here, we report a mutant of itRNATy2 (itRNATy2AUA) efficiently translation UAU tyrosine codon, giving rise proteins ncAA at their N-terminus. show that, cells expressing itRNATy2AUA, function as dual-use codon selectively ...

Archaea make glutaminyl-tRNA (Gln-tRNA(Gln)) in a two-step process; a non-discriminating glutamyl-tRNA synthetase (ND-GluRS) forms Glu-tRNA(Gln), while the heterodimeric amidotransferase GatDE converts this mischarged tRNA to Gln-tRNA(Gln). Many prokaryotes synthesize asparaginyl-tRNA (Asn-tRNA(Asn)) in a similar manner using a non-discriminating aspartyl-tRNA synthetase (ND-AspRS) and the hete...

The essential methanogen enzyme Sep-tRNA:Cys-tRNA synthase (SepCysS) converts O-phosphoseryl-tRNA(Cys) (Sep-tRNA(Cys)) into Cys-tRNA(Cys) in the presence of a sulfur donor. Likewise, Sep-tRNA:Sec-tRNA synthase converts O-phosphoseryl-tRNA(Sec) (Sep-tRNA(Sec)) to selenocysteinyl-tRNA(Sec) (Sec-tRNA(Sec)) using a selenium donor. While the Sep moiety of the aminoacyl-tRNA substrates is the same in...

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 mor...

The discovery of separate 5' and 3' halves of transfer RNA (tRNA) molecules-so-called split tRNA-in the archaeal parasite Nanoarchaeum equitans made us wonder whether ancestral tRNA was encoded on 1 or 2 genes. We performed a comprehensive phylogenetic analysis of tRNAs in 45 archaeal species to explore the relationship between the three types of tRNAs (nonintronic, intronic and split). We clas...

For most aminoacyl-tRNA synthetases (aaRS), their cognate tRNA is not obligatory to catalyze amino acid activation, with the exception of four class I (aaRS): arginyl-tRNA synthetase, glutamyl-tRNA synthetase, glutaminyl-tRNA synthetase and class I lysyl-tRNA synthetase. Furthermore, for arginyl-, glutamyl- and glutaminyl-tRNA synthetase, the integrated 3' end of the tRNA is necessary to activa...

INTRODUCTION................................................ 71 ORGANIZATION OF tRNA GENE REGIONS ................................................ o 71 Mapping of tRNA and rRNA Gene Clusters ................................................ 71 Large Clusters of tRNA genes-Evolutionary Considerations ................................................ 73 SEQUENCE ANALYSIS OF tRNA STRUCTURAL GENES .....

The tRNA structure contains conserved modifications that are responsible for its stability and are involved in the initiation and accuracy of the translation process. tRNA modification enzymes are prevalent in bacteria, archaea, and eukaryotes. tRNA Gm18 methyltransferase (TrmH) and tRNA m(1)G37 methyltransferase (TrmD) are prevalent and essential enzymes in bacterial populations. TrmH involves...

All mitochondrial tRNAs in Leishmania tarentolae are encoded in the nuclear genome and imported into the mitochondrion from the cytosol. One imported tRNA (tRNA(Trp)) is edited by a C to U modification at the first position of the anticodon. To determine the in vivo substrates for mitochondrial tRNA importation as well as tRNA editing, we examined the subcellular localization and extent of 5'- ...

Aminoacyl-tRNA synthetases catalyze the attachment of amino acids to their cognate tRNAs. In general, aminoacyl-tRNA synthetase assays require stoichiometric amounts of tRNA, which limits their sensitivity while increasing their cost. This requirement for stoichiometric amounts of tRNA can be alleviated if the aminoacyl-tRNA product is cleaved following the tRNA aminoacylation reaction, regener...