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Physical Sciences and Mathematics Commons

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Theses/Dissertations

2016

Portland State University

Transfer RNA

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Full-Text Articles in Physical Sciences and Mathematics

Quef And Quef-Like: Diverse Chemistries In A Common Fold, Adriana Bon Ramos Aug 2016

Quef And Quef-Like: Diverse Chemistries In A Common Fold, Adriana Bon Ramos

Dissertations and Theses

The tunneling fold (T-Fold) superfamily is a small superfamily of enzymes found in organisms encompassing all kingdoms of life. Seven members have been identified thus far. Despite sharing a common three-dimensional structure these enzymes perform very diverse chemistries.

QueF is a bacterial NADPH-dependent oxidoreductase that catalyzes the reduction of the nitrile group of 7-cyano-7-deazaguanine (preQ0) to a primary amine (preQ1) in the queuosine biosynthetic pathway. Previous work on this enzyme has revealed the mechanism of reaction but the cofactor binding residues remain unknown. The experiments discussed herein aim to elucidate the role of residues lysine 80, …


Discovery And Characterization Of The Proteins Involved In The Synthesis Of N⁶-Threonylcarbamoyl Adenosine, A Nucleoside Modification Of Trna, Christopher Wayne Deutsch Jul 2016

Discovery And Characterization Of The Proteins Involved In The Synthesis Of N⁶-Threonylcarbamoyl Adenosine, A Nucleoside Modification Of Trna, Christopher Wayne Deutsch

Dissertations and Theses

N6-threonylcarbamoyl adenosine (t6A) is a universally conserved tRNA modification found at position 37 of tRNAs which decode ANN codons. Structural studies have implicated its presence as a requirement for the disruption of a U-turn motif in certain tRNAs, leading to the formation of properly structured anticodon stem loop. This structure is proposed to enhance the base pairing between U36 of tRNA and A1 of the codon which aids in translational frame maintenance.

Despite significant effort since its discovery in the 1970s the enzymes involved in its biosynthesis remained undiscovered. Bioinformatic analysis identified two proteins as likely …