Genome-Wide Analysis of Fundamental Transcription Factors in Giardia lamblia

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Dr. Aaron Best

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Giardia lamblia is a unicellular parasite of the mammalian intestinal tract and is the most common parasitic intestinal disease in the United States. Giardia is an early-diverging eukaryote characterized by a two-stage life cycle. Giardia lacks the canonical RNA polymerase II transcription apparatus of eukaryotes and Archaea; its genome lacks TFIIB and has a highly degenerate TBP, raising questions as to how Giardia initiates RNA polymerase II transcription. We hypothesize that giardial BRF (TFIIB-related factor) could be substituting for TFIIB by playing a dual role in RNAP II and III initiation. Gene expression data from three time points in the giardial life cycle were generated using RNA-seq. Only a small subset of genes showed significantly different expression. Comparison with recent proteomic studies suggests limited regulation at the transcriptional level, giving way to post-transcriptional regulation as the primary control of gene expression, though continued study is necessary to test this hypothesis. Investigating transcription in Giardia will provide insight into the evolution of complex transcription systems in eukaryotes.


This research was supported by the Arnold and Mabel Beckman Foundation, the American Society for Microbiology, and National Science Foundation MRI Awards #1229585 and #1335890.

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