Poster abstracts

Poster number 15 submitted by Justin Davis

Telomerase RNA biogenesis requires direct interactions of a core group of nucleolar family proteins in the parasitic protist, Trypanosoma brucei

Justin A. Davis (Department of Biological Sciences, University of North Carolina at Charlotte ), Nitika, Andrew W. Truman, Kausik Chakrabarti (Department of Biological Sciences, University of North Carolina at Charlotte ), Andres V. Reyes, Shou-Ling Xu (Department of Plant Biology and Carnegie Mass Spectrometry Facility, Carnegie Institution for Science), Arpita Saha, Bibo Li (Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Arts Sciences, Cleveland State University,), Donald J. Wolfgeher (Department of Molecular Genetics and Cell Biology, The University of Chicago)

Telomeres are the nucleoprotein structures found at the ends of eukaryotic linear chromosomes. Telomeric dysfunction and instability poses a significant threat to the genome integrity of eukaryotes. Telomeres are maintained by the actions of the ribonucleoprotein enzyme telomerase. Unlike human somatic cells, telomerase is constantly active in parasitic protozoa, which makes these cells proliferate rapidly to establish chronic, long-term infections. Significantly shortened telomeres in the protozoan parasite Trypanosoma brucei (T. brucei) have been shown to affect antigenic variation, which facilitates the parasite’s ability to evade its host’s immune responses. We and others have identified and characterized the telomerase RNA (TR) and the reverse transcriptase protein component (TERT) of T. brucei telomerase. Our recent in vivo probing of T. brucei telomerase RNA (TbTR), revealed developmental specific TR structural changes, which are intimately linked to parasite development, telomerase activity and cell proliferation. Interestingly, we found that the telomerase catalytic subunit TERT does not partake in the TR folding process for telomere synthesis in the human infective form (bloodstream form) of T. brucei. To gain a global view of the proteome that might be responsible for biogenesis and assembly of T. brucei telomerase, we have now identified the global interactors of T. brucei telomerase reverse transcriptase (TbTERT) using an affinity-purification based mass spectrometry approach. This approach identified >100 interactors, including known orthologs from yeast, human and ciliate species that can bind TERT and the TR. Most surprisingly, we identified an array of snoRNPs that can carry out 2’-O-ribose methylation, which is required for proper folding, stability and RNA-protein interactions. Deletion of the C/D box domain of the Telomerase RNA impairs binding of snoRNP NOP58, suggesting its potential role in the maturation and structural changes in this RNA during the telomerase reaction cycle. Therefore, we hypothesize that these proteins are required for TbTR biogenesis and have the potential to act as chaperones for RNA folding in T. brucei telomerase

Keywords: Telomerase , Telomerase RNA , T brucei