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Smc5/6 Is a Telomere-Associated Complex that Regulates Sir4 Binding and TPE

SMC proteins constitute the core members of the Smc5/6, cohesin and condensin complexes. We demonstrate that Smc5/6 is present at telomeres throughout the cell cycle and its association with chromosome ends is dependent on Nse3, a subcomponent of the complex. Cells harboring a temperature sensitive...

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Published in:PLoS genetics 2016-08, Vol.12 (8), p.e1006268-e1006268
Main Authors: Moradi-Fard, Sarah, Sarthi, Jessica, Tittel-Elmer, Mireille, Lalonde, Maxime, Cusanelli, Emilio, Chartrand, Pascal, Cobb, Jennifer A
Format: Article
Language:English
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Summary:SMC proteins constitute the core members of the Smc5/6, cohesin and condensin complexes. We demonstrate that Smc5/6 is present at telomeres throughout the cell cycle and its association with chromosome ends is dependent on Nse3, a subcomponent of the complex. Cells harboring a temperature sensitive mutant, nse3-1, are defective in Smc5/6 localization to telomeres and have slightly shorter telomeres. Nse3 interacts physically and genetically with two Rap1-binding factors, Rif2 and Sir4. Reduction in telomere-associated Smc5/6 leads to defects in telomere clustering, dispersion of the silencing factor, Sir4, and a loss in transcriptional repression for sub-telomeric genes and non-coding telomeric repeat-containing RNA (TERRA). SIR4 recovery at telomeres is reduced in cells lacking Smc5/6 functionality and vice versa. However, nse3-1/ sir4 Δ double mutants show additive defects for telomere shortening and TPE indicating the contribution of Smc5/6 to telomere homeostasis is only in partial overlap with SIR factor silencing. These findings support a role for Smc5/6 in telomere maintenance that is separate from its canonical role(s) in HR-mediated events during replication and telomere elongation.
ISSN:1553-7404
1553-7390
1553-7404
DOI:10.1371/journal.pgen.1006268