Associate Professor

Juan D. Alfonzo

B.S., Indiana University- Bloomington, IN
Ph.D., Indiana University- Bloomington, IN
Post-doctoral Research, University of California, Los Angeles

The Alfonzo Lab

Editing & Modification of tRNA: Roles in Mitochondrial Biogenesis and Disease.

We are interested in RNA processing events that are unique to trypanosomes and could be exploited as targets for the design of therapies against protozoan diseases. To date, the Protozoa are responsible for the infection and death of millions of people worldwide. I am especially interested in two facets of RNA processing in trypanosomes: tRNA editing and tRNA modification.

The Mechanism of tRNA Editing

RNA editing involves any process by which the information content of a given transcript (mRNA, tRNA, etc.) is changed so that it will differ from that encoded in the genome. RNA editing occurs by a variety of chemically distinct post-transcriptional mechanisms including nucleotide insertion, deletions, base deaminations, and nucleotide exchange (to name a few) and plays an important role in the regulation of gene expression. In trypanosomes, I discovered that the nucleus-encoded tRNATrp undergoes an essential cytosine to uridine editing of the wobble position of the anticodon upon importation into the mitochondrion. Most notable, the deamination of cytosine to uridine at the anticodon allows the decoding of UGA codons as tryptophan. We are interested in the mechanism of tRNA editing and plan to use a genetic and biochemical approach to achieve a complete structure/function analysis of this process in trypanosomes

The Modifications of tRNA and Contribution to Mitochondrial Function

The functional importance of RNA modifications is evident from the large number of phylogenetically conserved modifications that occur in various cellular RNAs. Little is known about the role and extent of RNA modifications in early divergent eukaryotes. In addition, there are increasing numbers of reports linking tRNA modifications with mitochondrial diseases. I plan to use trypanosomes as a model system to study the role that specific tRNA modifications play in mitochondrial function. These studies will be the basis for examining the role site-specific tRNA modifications plays in mitochondrial function. The long-term goal is to utilize the exquisite specificity of these editing and modification enzymes for the long-term applications in gene therapy in humans.

In general, the emphasis of my laboratory will focus on the translation of RNA structure into RNA function in a biological system. Specifically, I hope to dissect the pathways involved in tRNA maturation, including editing and modification, to address issues involving molecular recognition. I firmly believe this research will not only uncover useful knowledge of basic cellular processes, but also provides the added incentive of great overall implications towards applications in medicine.

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