Poster abstracts
Poster number 107 submitted by Abby Primack
Initial characterization of a regulatory antisense transcript in Toxoplasma gondii
Abby S. Primack (Biological Sciences, University of Pittsburgh), Emily F. Klonicki (Biological Sciences, University of Pittsburgh), Jon P. Boyle (Biological Sciences, University of Pittsburgh)
Abstract:
The obligate, intracellular parasite Toxoplasma gondii infects 30% of the world’s population, is lethal to immunocompromised humans, and causes birth defects and abortion. After host cell invasion, the parasite forms a vacuole and associates with host mitochondria. Host-mitochondrial association (HMA+) is not present in all T. gondii strains and this has allowed us to use forward genetics to identify the responsible gene. The gene, MAF1, is highly expressed in HMA+ strains while the protein product is undetectable in HMA- negative strains. Although all HMA ± strains produce MAF1 transcript, HMA- strains produce a significantly smaller amount of transcript and a larger amount of antisense transcript as compared to HMA+ strains. We hypothesize that a product encoded in the antisense region suppresses MAF1 expression through transcriptional interference. To begin to test this hypothesis, we are characterizing the sense and antisense promoter activities of MAF1. Putative promoter sequences were transfected into T. gondii and promoter strength was quantified using a reporter assay. Through comprehensive sequencing, our results suggest that there are multiple antisense promoter paralogs within each strain. We also demonstrate that the antisense promoter is stronger than its sense counterpart, indicating that we have isolated a highly active antisense promoter region. Future work aims to further characterize MAF1 antisense promoter activity, and ultimately determine the impact of the antisense transcript on MAF1 expression and HMA.
References:
Pernas, L, Y. Adomako-Ankomah, A. J. Shastri, S. E. Ewald, M. Treeck, J. P. Boyle, J. C. Boothroyd. 2014. Toxoplasma effector MAF1 mediates recruitment of host mitochondria and impacts the host response. PLoS Biology 12(4): e1001845
Keywords: antisense transcript, pathogen, promoter