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Full-Text Articles in Molecular Biology
Probing The Genetic Code With Leucine Trna Variants, Peter Anderson Hall
Probing The Genetic Code With Leucine Trna Variants, Peter Anderson Hall
Electronic Thesis and Dissertation Repository
Mistranslation is an error in protein synthesis whereby the amino acids specified by the genetic code are misplaced by others in the growing polypeptide chain. The anticodon of tRNALeu can be altered allowing for the misincorporation of leucine at non-leucine codons. Observing the effect of tRNALeu variants on the viability of yeast and mammalian cells will provide information on their ability to cause mistranslation and potential relationship to genetic diseases. To explore this, a random pool of tRNALeu anticodonvariants was expressed in Saccharomyces cerevisiae. Furthermore, three mutant tRNALeu already sequenced from humans were expressed in …
Illuminating Transfer Rna Variants As Genetic Modifiers In Models Of Human Disease, Jeremy T. Lant
Illuminating Transfer Rna Variants As Genetic Modifiers In Models Of Human Disease, Jeremy T. Lant
Electronic Thesis and Dissertation Repository
Transfer RNAs (tRNAs) physically link the genetic code to an amino acid sequence, by recruiting amino acids to three-nucleotide codons in messenger RNAs. To ensure that the genetic code is translated as intended, tRNAs must be accurately aminoacylated and faithfully recognize codons in the ribosome during protein synthesis. Given the critical function of tRNAs, it has often been assumed that mutations in human tRNA genes would be either lethal to cells or not significantly impair tRNA function. My goal was to rigorously test this assumption in mammalian cell models, prompted by the recent discovery of unprecedented variation in human tRNA …
Implications And Applications Of Transfer Rna Variants That Mistranslate The Genetic Code, Matthew D. Berg
Implications And Applications Of Transfer Rna Variants That Mistranslate The Genetic Code, Matthew D. Berg
Electronic Thesis and Dissertation Repository
Genetic information is passed from DNA to RNA to protein through the processes of transcription and translation. Transfer RNAs (tRNA) are the adaptors that bring amino acids to the growing polypeptide chain during translation and decode the three base codons that define protein sequence. Mistranslation occurs when an amino acid different from what is specified by the genetic code is inserted into a protein. tRNA variants cause mistranslation by decreasing the accuracy of amino acid charging or by altering decoding at the ribosome. My goal was to characterize mistranslating tRNA variants, identify their effects on cells and determine mechanisms used …
Epitranscriptomic Writer Systems And Codon Bias Regulate The Response To Environmental Stress, Andrea Leonardi
Epitranscriptomic Writer Systems And Codon Bias Regulate The Response To Environmental Stress, Andrea Leonardi
Legacy Theses & Dissertations (2009 - 2024)
Epitranscriptomic marks in the form of enzyme-catalyzed modifications to RNA nucleosides can be important regulators of translation and play integral roles in the response to stress. Dynamic changes in tRNA modification status can regulate the translation of stress response proteins whose transcripts have distinct codon biases. The epitranscriptomic writer Alkylation repair homolog 8 (ALKBH8) plays a crucial part in the translation of codon biased transcripts, as it regulates stop codon recoding, which is a specialized form of translation used to generate selenoproteins. ALKBH8 modifies the wobble uridine of selenocysteine tRNA (tRNASec) to promote the decoding of an internal UGA codon …
The Role Of Trm9 In Stress Responses, Ashish Ravindra Patil
The Role Of Trm9 In Stress Responses, Ashish Ravindra Patil
Legacy Theses & Dissertations (2009 - 2024)
Cells need to respond appropriately to environmental changes in order to maintain homeostasis. The cellular response to an environmental stress is regulated at transcriptional, translational and post translational levels. The tRNA, which acts as an adaptor molecule between the mRNA and the protein, plays an important role in the translational regulation of cellular responses to stress and is one of the most heavily modified biomolecules. In Saccharomyces cerevisiae , the wobble uracil of the tRNA(3'-UCU-5') Arg, tRNA(3'-UUC-5') Glu and certain other specific tRNAs are modified to 5-methoxycarbonylmethyluridine (mcm5U) and 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U) residues by the tRNA methyltransferase 9 (Trm9). Modifications at …
Study Of Dynamic Processes In Protein Synthesis Using Heterogeneous Ribosome Specimens, Jie Fu
Study Of Dynamic Processes In Protein Synthesis Using Heterogeneous Ribosome Specimens, Jie Fu
Legacy Theses & Dissertations (2009 - 2024)
Single-particle reconstruction from cryo-electron microscopy (cryo-EM) images is a widely used technique in studying the structure of macromolecular complexes. This technique allows the visualization of molecules in their native hydrated state. The heterogeneity of two-dimensional projection images, resulting from the co-existence of different states of a macromolecular complex, remains a major obstacle, as it impairs the validity of reconstruction and limits the progress toward higher resolution. On the other hand, co-existing structures, if successfully extracted from a single dataset, can provide valuable information about the equilibrium and dynamics of the biological system being studied.
Separation And Quantification Of Queuine-Modified And Unmodified Transfer Rna Isoacceptors, Jorge Miguel Pereira De Oliveira Da Silva Santos
Separation And Quantification Of Queuine-Modified And Unmodified Transfer Rna Isoacceptors, Jorge Miguel Pereira De Oliveira Da Silva Santos
Chemistry & Biochemistry Theses & Dissertations
The discovery of a base-exchange modification in the first position of the anticodon of four transfer RNA (tRNA) isoacceptor families has been shown to be correlated with a decrease in the rate of cell division in several tumorigenic tissues. This fact led to the hypothesis that wobbling in the anticodon might be a control point wich mediates the rate of translation. A suitable method for separation of different tRNA isoacceptor families had to be created in order to generate a means for quantitatively measuring degrees of this base modification in tRNA. Radio labelled amino acids were used to charge tRNA …
Separation Of Transfer Rna Isoacceptors By Reversed Phase W-Porex C-4 High Pressure Liquid Chromatography, Christine D. Witte
Separation Of Transfer Rna Isoacceptors By Reversed Phase W-Porex C-4 High Pressure Liquid Chromatography, Christine D. Witte
Chemistry & Biochemistry Theses & Dissertations
Transfer RNA (tRNA), is a complex class of small molecules which have been proven to play a major role in protein synthesis. Transfer RNA is composed of 20 families of isoacceptors which may recognize only one particular amino acid. This family of isoacceptors may differ from each other by primary sequence or modified nucleosides. Queuine is a modified nucleoside which is found in the anticodon regions of tRNA isoacceptors for asparagine, aspartic acid, tyrosine and histidine. Queuine has gained the interest of many researchers since queuine deficient tRNA was found in many neoplastic and undifferentiated cell-lines. It is often difficult …
Regulation Of Queuine Insertion Into Transfer Rna: Effects Of Tumor Promoters, Bonnie Jean Brooks
Regulation Of Queuine Insertion Into Transfer Rna: Effects Of Tumor Promoters, Bonnie Jean Brooks
Chemistry & Biochemistry Theses & Dissertations
The purpose of this study was to treat normal human fibroblasts with known tumor promoters and observe queuine modification of tRNA. The queuine insertion enzyme, tRNAguanine ribosyltransferase, was studied in vivo and in vitro. Tumor promoter-treated human fibroblast cultures exhibited variable queuine-insertion rates with a transient inhibition that correlated with variable levels of queuine modified tRNA over time in culture from passages 3 — 8. In contrast the in vitro studies showed that phorbol cetera and saccharin actually increased insertion with strong evidence indicating phosphorylation as a positive modulating force of the enzyme activity. It is proposed that chronic stimulation …
Hypoxanthine-Induced Differentiation Of Cultured Human Leukemia Cells, Gayle Jennette Singleton
Hypoxanthine-Induced Differentiation Of Cultured Human Leukemia Cells, Gayle Jennette Singleton
Chemistry & Biochemistry Theses & Dissertations
Human cultured leukemia cells appear to have a decreased amount of inosine in their tRNA. When cells with inosine deficient tRNA are placed in a hypoxanthine fortified media, they incorporate hypoxanthine into their tRNA by the action of the enzyme tRNA-hypoxanthine ribosyl transferase. This generates the nucleoside inosine in the tRNA. The cultured human leukemia cell lines, CCRF-CEM, HL-60, and HGPRT(-) HL- 60, incorporate hypoxanthine into their tRNA, as determined by tRNA isolation, hydrolysis, and HPLC analysis. Hypoxanthine treatment dramatically inhibited cell growth in conjunction with partial induction of differentiation in the CCRF-CEM, HL-60, and HGPRT ( - ) HL-60 …