Human Fbh1 helicase contributes to genome maintenance via pro- and anti-recombinase activities.
Homologous recombination (HR) is essential for faithful repair of DNA lesions yet must be kept in check, as unrestrained HR may compromise genome integrity and lead to premature aging or cancer. To limit unscheduled HR, cells possess DNA helicases capable of preventing excessive recombination. In this study, we show that the human Fbh1 (hFbh1) helicase accumulates at sites of DNA damage or replication stress in a manner dependent fully on its helicase activity and partially on its conserved F box. hFbh1 interacted with single-stranded DNA (ssDNA), the formation of which was required for hFbh1 recruitment to DNA lesions. Conversely, depletion of endogenous Fbh1 or ectopic expression of helicase-deficient hFbh1 attenuated ssDNA production after replication block. Although elevated levels of hFbh1 impaired Rad51 recruitment to ssDNA and suppressed HR, its small interfering RNA-mediated depletion increased the levels of chromatin-associated Rad51 and caused unscheduled sister chromatid exchange. Thus, by possessing both pro- and anti-recombinogenic potential, hFbh1 may cooperate with other DNA helicases in tightly controlling cellular HR activity.
Fugger
Kasper
K
Institute of Cancer Biology and Center for Genotoxic Stress Research, Danish Cancer Society, DK-2100 Copenhagen, Denmark.
Mistrik
Martin
M
Danielsen
Jannie Rendtlew
JR
Dinant
Christoffel
C
Falck
Jacob
J
Bartek
Jiri
J
Lukas
Jiri
J
Mailand
Niels
N
D000818:Animals; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D004249:DNA Damage; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015894:Genome, Human; D006801:Humans; D034622:RNA Interference; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D045522:Recombinases / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic
D002843:Chromatin; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D045522:Recombinases; D051135:Rad51 Recombinase; D004265:DNA Helicases; C464443:FBH1 protein, human