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Homologous DNA strand exchange activity of the human mitochondrial DNA helicase TWINKLE

A crucial component of the human mitochondrial DNA replisome is the ring-shaped helicase TWINKLE—a phage T7-gene 4-like protein expressed in the nucleus and localized in the human mitochondria. Our previous studies showed that despite being a helicase, TWINKLE has unique DNA annealing activity. At t...

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Detalles Bibliográficos
Autores principales: Sen, Doyel, Patel, Gayatri, Patel, Smita S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4872091/
https://www.ncbi.nlm.nih.gov/pubmed/26887820
http://dx.doi.org/10.1093/nar/gkw098
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author Sen, Doyel
Patel, Gayatri
Patel, Smita S.
author_facet Sen, Doyel
Patel, Gayatri
Patel, Smita S.
author_sort Sen, Doyel
collection PubMed
description A crucial component of the human mitochondrial DNA replisome is the ring-shaped helicase TWINKLE—a phage T7-gene 4-like protein expressed in the nucleus and localized in the human mitochondria. Our previous studies showed that despite being a helicase, TWINKLE has unique DNA annealing activity. At the time, the implications of DNA annealing by TWINKLE were unclear. Herein, we report that TWINKLE uses DNA annealing function to actively catalyze strand-exchange reaction between the unwinding substrate and a homologous single-stranded DNA. Using various biochemical experiments, we demonstrate that the mechanism of strand-exchange involves active coupling of unwinding and annealing reactions by the TWINKLE. Unlike strand-annealing, the strand-exchange reaction requires nucleotide hydrolysis and greatly stimulated by short region of homology between the recombining DNA strands that promote joint molecule formation to initiate strand-exchange. Furthermore, we show that TWINKLE catalyzes branch migration by resolving homologous four-way junction DNA. These four DNA modifying activities of TWINKLE: strand-separation, strand-annealing, strand-exchange and branch migration suggest a dual role of TWINKLE in mitochondrial DNA maintenance. In addition to playing a major role in fork progression during leading strand DNA synthesis, we propose that TWINKLE is involved in recombinational repair of the human mitochondrial DNA.
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spelling pubmed-48720912016-05-27 Homologous DNA strand exchange activity of the human mitochondrial DNA helicase TWINKLE Sen, Doyel Patel, Gayatri Patel, Smita S. Nucleic Acids Res Genome Integrity, Repair and Replication A crucial component of the human mitochondrial DNA replisome is the ring-shaped helicase TWINKLE—a phage T7-gene 4-like protein expressed in the nucleus and localized in the human mitochondria. Our previous studies showed that despite being a helicase, TWINKLE has unique DNA annealing activity. At the time, the implications of DNA annealing by TWINKLE were unclear. Herein, we report that TWINKLE uses DNA annealing function to actively catalyze strand-exchange reaction between the unwinding substrate and a homologous single-stranded DNA. Using various biochemical experiments, we demonstrate that the mechanism of strand-exchange involves active coupling of unwinding and annealing reactions by the TWINKLE. Unlike strand-annealing, the strand-exchange reaction requires nucleotide hydrolysis and greatly stimulated by short region of homology between the recombining DNA strands that promote joint molecule formation to initiate strand-exchange. Furthermore, we show that TWINKLE catalyzes branch migration by resolving homologous four-way junction DNA. These four DNA modifying activities of TWINKLE: strand-separation, strand-annealing, strand-exchange and branch migration suggest a dual role of TWINKLE in mitochondrial DNA maintenance. In addition to playing a major role in fork progression during leading strand DNA synthesis, we propose that TWINKLE is involved in recombinational repair of the human mitochondrial DNA. Oxford University Press 2016-05-19 2016-02-16 /pmc/articles/PMC4872091/ /pubmed/26887820 http://dx.doi.org/10.1093/nar/gkw098 Text en © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research. http://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
spellingShingle Genome Integrity, Repair and Replication
Sen, Doyel
Patel, Gayatri
Patel, Smita S.
Homologous DNA strand exchange activity of the human mitochondrial DNA helicase TWINKLE
title Homologous DNA strand exchange activity of the human mitochondrial DNA helicase TWINKLE
title_full Homologous DNA strand exchange activity of the human mitochondrial DNA helicase TWINKLE
title_fullStr Homologous DNA strand exchange activity of the human mitochondrial DNA helicase TWINKLE
title_full_unstemmed Homologous DNA strand exchange activity of the human mitochondrial DNA helicase TWINKLE
title_short Homologous DNA strand exchange activity of the human mitochondrial DNA helicase TWINKLE
title_sort homologous dna strand exchange activity of the human mitochondrial dna helicase twinkle
topic Genome Integrity, Repair and Replication
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4872091/
https://www.ncbi.nlm.nih.gov/pubmed/26887820
http://dx.doi.org/10.1093/nar/gkw098
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