The structure and integrity of DNA is of immense biological and biomedical importance. It is therefore essential to identify and to characterize the enzymes that alter DNA structure. For instance, DNA helicases are a large and diverse group of ATP-driven motor proteins that unwind DNA and participate in a broad range of biological processes. The study of helicases has been and will continue to be a critically important area of research. The human HARP protein (also known as SMARCAL1 and ATP-dependent ATPase A) was recently found to be an ATP-driven annealing helicase - that is, a novel enzyme that catalyzes the rewinding of complementary ssDNA that is bound by replication protein A, the major ssDNA- binding protein in the nucleus. Thus, HARP is a motor protein that acts in the opposite manner as DNA helicases. HARP is a distant member of the SNF2 family of ATP-dependent motor proteins. Mutations in the HARP gene are responsible for a rare autosomal recessive pleiotropic disorder known as Schimke immuno-osseous dysplasia (SIOD). The available data suggest that HARP contributes to the maintenance of genome integrity, and that SIOD is caused by a deficiency in the annealing helicase activity of HARP. More recent studies have led to the discovery of a second annealing helicase, termed AH2, for annealing helicase 2. AH2 is a novel protein that has not yet been reported in the literature. Unlike HARP, AH2 does not bind to RPA. It therefore appears likely that HARP and AH2 will have distinct biological functions. The long-term objective of this project is to determine the factors and biological phenomena that are associated with annealing helicases.
The specific aims are as follows: to investigate the function of AH2 as well as the relation between AH2 and HARP;to develop new assays for annealing helicase activity and to analyze the effects of annealing helicases on different biochemical and biological processes;and to search for new annealing helicases, which includes DNA annealing helicases as well as DNA-RNA annealing helicases. These studies should provide novel and important advances in this emerging area of biomedical research.

Public Health Relevance

This project involves the analysis of a newly-discovered enzyme - a motor protein that rewinds the DNA double helix. Humans that are deficient in this enzyme have a disorder known as Schimke immuno-osseous dysplasia, which typically leads to death in early childhood. The proposed research will expand our understanding of these DNA rewinding enzymes as well as investigate their potential application for the treatment of diseases such as cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM058272-15
Application #
8400888
Study Section
Molecular Genetics A Study Section (MGA)
Program Officer
Carter, Anthony D
Project Start
1999-01-01
Project End
2014-12-31
Budget Start
2013-01-01
Budget End
2013-12-31
Support Year
15
Fiscal Year
2013
Total Cost
$310,173
Indirect Cost
$102,698
Name
University of California San Diego
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Kassavetis, George A; Kadonaga, James T (2014) The annealing helicase and branch migration activities of Drosophila HARP. PLoS One 9:e98173
Quan, Jinhua; Yusufzai, Timur (2014) HARP preferentially co-purifies with RPA bound to DNA-PK and blocks RPA phosphorylation. Epigenetics 9:693-7
Wang, Lanfeng; Limbo, Oliver; Fei, Jia et al. (2014) Regulation of the Rhp26ERCC6/CSB chromatin remodeler by a novel conserved leucine latch motif. Proc Natl Acad Sci U S A 111:18566-71
Torigoe, Sharon E; Patel, Ashok; Khuong, Mai T et al. (2013) ATP-dependent chromatin assembly is functionally distinct from chromatin remodeling. Elife 2:e00863
Torigoe, Sharon E; Urwin, Debra L; Ishii, Haruhiko et al. (2011) Identification of a rapidly formed nonnucleosomal histone-DNA intermediate that is converted into chromatin by ACF. Mol Cell 43:638-48
Yusufzai, Timur; Kadonaga, James T (2011) Branching out with DNA helicases. Curr Opin Genet Dev 21:214-8
Yusufzai, Timur; Kadonaga, James T (2010) Annealing helicase 2 (AH2), a DNA-rewinding motor with an HNH motif. Proc Natl Acad Sci U S A 107:20970-3
Rattner, Barbara P; Yusufzai, Timur; Kadonaga, James T (2009) HMGN proteins act in opposition to ATP-dependent chromatin remodeling factors to restrict nucleosome mobility. Mol Cell 34:620-6
Yusufzai, Timur; Kong, Xiangduo; Yokomori, Kyoko et al. (2009) The annealing helicase HARP is recruited to DNA repair sites via an interaction with RPA. Genes Dev 23:2400-4
Zhang, Yong; Moqtaderi, Zarmik; Rattner, Barbara P et al. (2009) Intrinsic histone-DNA interactions are not the major determinant of nucleosome positions in vivo. Nat Struct Mol Biol 16:847-52

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