Characterization of telomerase RNP in Arabidopsis thaliana

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Title: Characterization of telomerase RNP in Arabidopsis thaliana
Author: Kannan, Kalpana
Abstract: Telomeres are critical for the integrity of eukaryotic genomes . They function to protect chromosome ends from DNA damage surveillance and inappropriate repair . Telomeres are maintained by the specialized ribonucleoprotein complex telomerase . Without telomerase , telomere shortening would ultimately lead to compromised genome stability and cellular senescence . Therefore , telomerase function is necessary for extension of the proliferative capacity of the cell . In this dissertation , we describe the characterization of core components of telomerase ribonucleoprotein complex in the flowering plant , Arabidopsis thaliana . We find that dyskerin , one of the core telomerase components in humans is also conserved in Arabidopsis telomerase . Arabidopsis dyskerin associates with the telomerase RNP in an RNA -dependent manner and is required for telomere length maintenance in this organism . We also describe the characterization of another core telomerase component , the telomerase RNA subunits (TERs ) . Unexpectedly , we uncovered two distinct TER subunits that share a region of high identity . The two TERs named TER1G7 and TER5G2 , based on their chromosomal positions , display differences in their expression levels and their association with telomere -related proteins . Both TERs can serve as templates for telomerase in vitro . Through genetic analyses , we show a templating function for TER1G7 in vivo and a novel role for TER5G2 as a negative regulator of telomerase . Finally , the presence of TER genes in other plant species was investigated and evidence for duplication of TER genes in plants closely related to Arabidopsis was obtained . We also show evidence for a template mutation in Asparagus TER that could lead to variant repeats in this organism . In summary , the studies presented in this dissertation reveal that Arabidopsis telomerase shares both similarities and differences with other telomerase RNPs , making it an exciting model system for study of telomere biology .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2008 -12 -95
Date: 2010-01-14


Characterization of telomerase RNP in Arabidopsis thaliana. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2008 -12 -95 .

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