NIH VideoCast - Bloom Helicase Mediates Formation of Large Single-Stranded DNA Loops During DNA End Processing

Skip Navigation

Bloom Helicase Mediates Formation of Large Single-Stranded DNA Loops During DNA End Processing

Loading... Loading video...

322 Views

Air date:	Wednesday, January 19, 2022, 3:00:00 PM Time displayed is Eastern Time, Washington DC Local
Views:	Total views: 322 (218 Live, 104 On-demand)
Category:	WALS - Wednesday Afternoon Lectures
Runtime:	01:08:27
Closed captioning:	Check box to display CC outside of the video Note: You can drag the captioning window around and resize it
Description:	NIH Wednesday Afternoon Lecture Series Dr. Greene is a professor in the Department of Biochemistry and Molecular Biophysics at Columbia University in New York. His lab uses single-molecule optical microscopy to study fundamental interactions between proteins and nucleic acids, in essence to observe individual protein molecules or protein complexes as they interact with their DNA substrates. This technique is revealing the molecular mechanisms that cells use to repair, maintain, and decode their genetic information. Homologous recombination (HR) is essential for maintenance of genome integrity. Rad51 paralogs fulfill a conserved but undefined role in HR, and their mutations are associated with increased cancer risk in humans. We have used single-molecule imaging to reveal that the Saccharomyces cerevisiae Rad51 paralog complex Rad55-Rad57 promotes assembly of Rad51 recombinase filament through transient interactions, providing evidence that it acts like a classical molecular chaperone. Srs2 is an ATP-dependent anti-recombinase that downregulates HR by actively dismantling Rad51 filaments. Contrary to the current model, we find that Rad55-Rad57 does not physically block the movement of Srs2. Instead, Rad55-Rad57 promotes rapid re-assembly of Rad51 filaments after their disruption by Srs2. Our findings support a model in which Rad51 is in flux between free and single-stranded DNA (ssDNA)-bound states, the rate of which is controlled dynamically though the opposing actions of Rad55-Rad57 and Srs2. For more information go to https://oir.nih.gov/wals

NLM Title:	Bloom helicase mediates formation of large single-stranded DNA loops during DNA end processing / Eric C. Greene.
Author:	Greene, Eric C. National Institutes of Health (U.S.),
Publisher:
Abstract:	(CIT): Dr. Greene is a professor in the Department of Biochemistry and Molecular Biophysics at Columbia University in New York. His lab uses single-molecule optical microscopy to study fundamental interactions between proteins and nucleic acids, in essence to observe individual protein molecules or protein complexes as they interact with their DNA substrates. This technique is revealing the molecular mechanisms that cells use to repair, maintain, and decode their genetic information. Homologous recombination (HR) is essential for maintenance of genome integrity. Rad51 paralogs fulfill a conserved but undefined role in HR, and their mutations are associated with increased cancer risk in humans. We have used single-molecule imaging to reveal that the Saccharomyces cerevisiae Rad51 paralog complex Rad55-Rad57 promotes assembly of Rad51 recombinase filament through transient interactions, providing evidence that it acts like a classical molecular chaperone. Srs2 is an ATP-dependent anti-recombinase that downregulates HR by actively dismantling Rad51 filaments. Contrary to the current model, we find that Rad55-Rad57 does not physically block the movement of Srs2. Instead, Rad55-Rad57 promotes rapid re-assembly of Rad51 filaments after their disruption by Srs2. Our findings support a model in which Rad51 is in flux between free and single-stranded DNA (ssDNA)-bound states, the rate of which is controlled dynamically though the opposing actions of Rad55-Rad57 and Srs2.
Subjects:	DNA Breaks, Single-Stranded DNA End-Joining Repair--genetics DNA Helicases--metabolism DNA Repair Enzymes--physiology DNA, Single-Stranded--genetics
Publication Types:	Lecture Webcast

NLM Classification:	QU 137
NLM ID:	9918351572606676
CIT Live ID:	44192
Permanent link:	https://videocast.nih.gov/watch=44192

Related Videos...