The ancient essential process of ribosomal protein synthesis requires twenty sets of aminoacyl-tRNAs (aa-tRNAs), one for each canonical amino acid. Since Crick proposed his adaptor hypothesis (1) it was commonly accepted that all organisms possess twenty aaRSs, each enzyme specific for attaching one amino acid to tRNA. It is now clear that aa-tRNA formation is more varied, as the biosynthetic r...

INVESTIGATING THE GLUTAMINE-TRNA (GLUTAMINE) SYNTHESIS APPARTUSOF THE HUMAN PATHOGEN HELICOBACTER PYLORIby NILESH JOSHIAugust 2012Advisor: Tamara L. HendricksonMajor: ChemistryDegree: Master of ScienceAccurate protein biosynthesis is a vital process to all cellular life. Aminoacyl-tRNAs are at the heart of this process: A correctly formed aminoacyl-tRNA is critic...

Two transglutaminases (TGs), factor XIIIA (FXIIIA) and TG2, undergo physiologic upregulation in growth plate hypertrophic chondrocytes, and pathological upregulation in osteoarthritic cartilage. Externalization of guanine-nucleotide-bound TG2 drives chondrocyte maturation to hypertrophy, a state linked to matrix remodeling and calcification. Here, we tested the hypothesis that FXIIIA also promo...

Transglutaminases (TGMs) catalyze Ca2+-dependent transamidation of proteins with specified roles in blood clotting (F13a) and in cornification (TGM1, TGM3). The ubiquitous TGM2 has well described enzymatic and non-enzymatic functions but in-spite of numerous studies its physiological function in humans has not been defined. We compared data on non-synonymous single nucleotide variations (nsSNVs...

The intracellular distribution of glutaminyl-tRNA synthetases and their role in mitochondrial tRNA import were evaluated in the ancient eukaryote Leishmania tarentolae. The following results were obtained: (i) Glutaminyl-tRNA synthetase was detected in leishmanial mitochondria. This was unexpected because it has been postulated that, in organelles, Gln-tRNAGln is not formed by direct acylation ...

Transglutaminase 2 (TG2) is the most widely distributed and most abundantly expressed member of the transglutaminase family of enzymes, a group of intracellular and extracellular proteins that catalyze the Ca²⁺-dependent posttranslational modification of proteins. It is a unique member of the transglutaminase family owing to its specialized biochemical, structural and functional elements, ubiqu...

Opposing cellular responses are typically regulated by distinct sets of genes. However, tissue transglutaminase (TGase) provides an interesting example of a single gene product that has been implicated both in affording protection against cellular insults as well as in promoting cell death. Here, we shed some light on how these conflicting activities might be manifested by demonstrating that al...

The availability of highly purified leucine aminopeptidase (LAP)’ from swine kidney (3) has made it possible to study the action of this enzyme on protein and polypeptide substrates. By analogy with its action on amino acid amides and small peptides, the aminopeptidase should possess no endopeptidase activity and should hydrolyze only those peptide bonds which are adjacent to a free a-amino gro...

T-box riboswitches control transcription of downstream genes through the tRNA-binding formation of terminator or antiterminator structures. Previously reported T-boxes were described as single-specificity riboswitches that can bind specific tRNA anticodons through codon-anticodon interactions with the nucleotide triplet of their specifier loop (SL). However, the possibility that T-boxes might e...

Transglutaminases catalyze the posttranslational modification of proteins by transamidation of available glutamine residues. This action results primarily in the formation of epsilon-(gamma-glutamyl)lysine cross-links but includes the incorporation of polyamines into suitable protein substrates as well. The covalent isopeptide crosslink is stable and resistant to proteolysis, thereby increasing...