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Binding and melting of D-loops by the Bloom syndrome helicase.

TitleBinding and melting of D-loops by the Bloom syndrome helicase.
Publication TypeJournal Article
Year of Publication2000
Authorsvan Brabant AJ, Ye T, Sanz M, III JLGerman, Ellis NA, Holloman WK
JournalBiochemistry
Volume39
Issue47
Pagination14617-25
Date Published2000 Nov 28
ISSN0006-2960
KeywordsAdenosine Triphosphatases, Bloom Syndrome, DNA Damage, DNA Helicases, DNA-Binding Proteins, Humans, Models, Genetic, Nucleic Acid Conformation, Nucleic Acid Heteroduplexes, Protein Binding, Rad51 Recombinase, Recombination, Genetic, RecQ Helicases, Substrate Specificity
Abstract

Bloom syndrome is a rare autosomal disorder characterized by predisposition to cancer and genomic instability. BLM, the structural gene mutated in individuals with the disorder, encodes a DNA helicase belonging to the RecQ family of helicases. These helicases have been established to serve roles in both promoting and preventing recombination. Mounting evidence has implicated a function for BLM during DNA replication; specifically, BLM might be involved in rescuing stalled or collapsed replication forks by a recombination-based mechanism. We have tested this idea by examining the binding and melting activity of BLM on oligonucleotide substrates containing D-loops, DNA structures that model the presumed initial intermediate formed during homologous recombination. We find that BLM preferentially melts those D-loops that are formed more favorably by the strand exchange protein Rad51, but whose polarity could be less favorable for enabling restoration of an active replication fork. We propose a model in which BLM selectively dissociates recombination intermediates likely to be unfavorable for recombination-promoted replication.

Alternate JournalBiochemistry
PubMed ID11087418
Grant ListCA50897 / CA / NCI NIH HHS / United States
GM42482 / GM / NIGMS NIH HHS / United States

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