Genetic Study of Four Candidate Holliday Junction Processing Proteins in the Thermophilic Crenarchaeon <i>Sulfolobus acidocaldarius</i>

Homologous recombination (HR) is thought to be important for the repair of stalled replication forks in hyperthermophilic archaea. Previous biochemical studies identified two branch migration helicases (Hjm and PINA) and two Holliday junction (HJ) resolvases (Hjc and Hje) as HJ-processing proteins;...

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Main Authors: Ryo Matsuda, Shoji Suzuki, Norio Kurosawa
Format: Article
Language:English
Published: MDPI AG 2022-01-01
Series:International Journal of Molecular Sciences
Subjects:
Online Access:https://www.mdpi.com/1422-0067/23/2/707
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author Ryo Matsuda
Shoji Suzuki
Norio Kurosawa
author_facet Ryo Matsuda
Shoji Suzuki
Norio Kurosawa
author_sort Ryo Matsuda
collection DOAJ
description Homologous recombination (HR) is thought to be important for the repair of stalled replication forks in hyperthermophilic archaea. Previous biochemical studies identified two branch migration helicases (Hjm and PINA) and two Holliday junction (HJ) resolvases (Hjc and Hje) as HJ-processing proteins; however, due to the lack of genetic evidence, it is still unclear whether these proteins are actually involved in HR in vivo and how their functional relation is associated with the process. To address the above questions, we constructed <i>hjc</i>-, <i>hje</i>-, <i>hjm</i>-, and <i>pina</i> single-knockout strains and double-knockout strains of the thermophilic crenarchaeon <i>Sulfolobus acidocaldarius</i> and characterized the mutant phenotypes. Notably, we succeeded in isolating the <i>hjm</i>- and/or <i>pina</i>-deleted strains, suggesting that the functions of Hjm and PINA are not essential for cellular growth in this archaeon, as they were previously thought to be essential. Growth retardation in Δ<i>pina</i> was observed at low temperatures (cold sensitivity). When deletion of the HJ resolvase genes was combined, Δ<i>pina</i> Δ<i>hjc</i> and Δ<i>pina</i> Δ<i>hje</i> exhibited severe cold sensitivity. Δ<i>hjm</i> exhibited severe sensitivity to interstrand crosslinkers, suggesting that Hjm is involved in repairing stalled replication forks, as previously demonstrated in euryarchaea. Our findings suggest that the function of PINA and HJ resolvases is functionally related at lower temperatures to support robust cellular growth, and Hjm is important for the repair of stalled replication forks in vivo.
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spelling doaj.art-4104d46cb3604d4e8bdd04fefe1ab8212023-11-23T14:02:57ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672022-01-0123270710.3390/ijms23020707Genetic Study of Four Candidate Holliday Junction Processing Proteins in the Thermophilic Crenarchaeon <i>Sulfolobus acidocaldarius</i>Ryo Matsuda0Shoji Suzuki1Norio Kurosawa2Department of Environmental Engineering for Symbiosis, Graduate School of Science and Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, JapanDepartment of Environmental Engineering for Symbiosis, Graduate School of Science and Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, JapanDepartment of Environmental Engineering for Symbiosis, Graduate School of Science and Engineering, Soka University, 1-236 Tangi-machi, Hachioji, Tokyo 192-8577, JapanHomologous recombination (HR) is thought to be important for the repair of stalled replication forks in hyperthermophilic archaea. Previous biochemical studies identified two branch migration helicases (Hjm and PINA) and two Holliday junction (HJ) resolvases (Hjc and Hje) as HJ-processing proteins; however, due to the lack of genetic evidence, it is still unclear whether these proteins are actually involved in HR in vivo and how their functional relation is associated with the process. To address the above questions, we constructed <i>hjc</i>-, <i>hje</i>-, <i>hjm</i>-, and <i>pina</i> single-knockout strains and double-knockout strains of the thermophilic crenarchaeon <i>Sulfolobus acidocaldarius</i> and characterized the mutant phenotypes. Notably, we succeeded in isolating the <i>hjm</i>- and/or <i>pina</i>-deleted strains, suggesting that the functions of Hjm and PINA are not essential for cellular growth in this archaeon, as they were previously thought to be essential. Growth retardation in Δ<i>pina</i> was observed at low temperatures (cold sensitivity). When deletion of the HJ resolvase genes was combined, Δ<i>pina</i> Δ<i>hjc</i> and Δ<i>pina</i> Δ<i>hje</i> exhibited severe cold sensitivity. Δ<i>hjm</i> exhibited severe sensitivity to interstrand crosslinkers, suggesting that Hjm is involved in repairing stalled replication forks, as previously demonstrated in euryarchaea. Our findings suggest that the function of PINA and HJ resolvases is functionally related at lower temperatures to support robust cellular growth, and Hjm is important for the repair of stalled replication forks in vivo.https://www.mdpi.com/1422-0067/23/2/707hyperthermophilic archaea<i>Sulfolobus acidocaldarius</i>homologous recombinationHolliday junctionstalled replication fork
spellingShingle Ryo Matsuda
Shoji Suzuki
Norio Kurosawa
Genetic Study of Four Candidate Holliday Junction Processing Proteins in the Thermophilic Crenarchaeon <i>Sulfolobus acidocaldarius</i>
International Journal of Molecular Sciences
hyperthermophilic archaea
<i>Sulfolobus acidocaldarius</i>
homologous recombination
Holliday junction
stalled replication fork
title Genetic Study of Four Candidate Holliday Junction Processing Proteins in the Thermophilic Crenarchaeon <i>Sulfolobus acidocaldarius</i>
title_full Genetic Study of Four Candidate Holliday Junction Processing Proteins in the Thermophilic Crenarchaeon <i>Sulfolobus acidocaldarius</i>
title_fullStr Genetic Study of Four Candidate Holliday Junction Processing Proteins in the Thermophilic Crenarchaeon <i>Sulfolobus acidocaldarius</i>
title_full_unstemmed Genetic Study of Four Candidate Holliday Junction Processing Proteins in the Thermophilic Crenarchaeon <i>Sulfolobus acidocaldarius</i>
title_short Genetic Study of Four Candidate Holliday Junction Processing Proteins in the Thermophilic Crenarchaeon <i>Sulfolobus acidocaldarius</i>
title_sort genetic study of four candidate holliday junction processing proteins in the thermophilic crenarchaeon i sulfolobus acidocaldarius i
topic hyperthermophilic archaea
<i>Sulfolobus acidocaldarius</i>
homologous recombination
Holliday junction
stalled replication fork
url https://www.mdpi.com/1422-0067/23/2/707
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