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Factors Influencing the Recombinational Expansion and Spread of Telomeric Tandem Arrays in Kluyveromyces lactis (2003)
| Citations: | 9 - 4 self |
BibTeX
@MISC{Natarajan03factorsinfluencing,
author = {Shobhana Natarajan and Cindy Groff-vindman and Michael J. Mceachern},
title = {Factors Influencing the Recombinational Expansion and Spread of Telomeric Tandem Arrays in Kluyveromyces lactis},
year = {2003}
}
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Abstract
We have previously shown that DNA circles containing telomeric repeats and a marker gene can promote the recombinational elongation of telomeres in Kluyveromyces lactis by a mechanism proposed to involve rollingcircle DNA synthesis. Wild-type cells acquire a long tandem array at a single telomere, while telomerase deletion (ter1-�) cells, acquire an array and also spread it to multiple telomeres. In this study, we further examine the factors that affect the formation and spread of telomeric tandem arrays. We show that a telomerase � strain with short telomeres and high levels of subtelomeric gene conversion can efficiently form and spread arrays, while a telomere fusion mutant is not efficient at either process. This indicates that an elevated level of gene conversion near telomeres is required for spreading but that growth senescence and a tendency to elongate telomeres in the absence of exogenously added circles are not. Surprisingly, telomeric repeats are frequently deleted from a transforming URA3-telomere circle at or prior to the time of array formation by a mechanism dependent upon the presence of subtelomeric DNA in the circle. We further show that in a ter1- � strain, long tandem arrays can arise from telomeres initially containing a single-copy insert of the URA3-telomere sequence. However, the reduced rate of array formation in such strains suggests that single-copy inserts are not typical intermediates in arrays formed from URA3-telomere circles. Using heteroduplex circles, we have demonstrated that either strand of a URA3-telomere circle can be utilized to form
Keyphrases
kluyveromyces lactis telomeric tandem array ura3-telomere circle recombinational expansion single-copy insert array formation telomeric repeat telomerase deletion gene conversion single telomere heteroduplex circle long tandem array typical intermediate telomerase strain subtelomeric gene conversion ter1 strain reduced rate telomere fusion mutant rollingcircle dna synthesis ura3-telomere sequence subtelomeric dna growth senescence dna circle recombinational elongation elevated level high level wild-type cell marker gene tandem array short telomere multiple telomere
