In multicellular organisms, genomic stability is maintained by the combined action of an accurate DNA replication machinery and a complex network of DNA repair pathways. DNA joining is an essential step in DNA replication, in DNA excision repair pathways and in genetic recombination. Three human genes encoding DNA ligases have been identified. Previous biochemical studies have indicated that the product of the LIG1 gene functions in DNA replication. These observations were supported by the abnormal accumulation of Okazaki fragments in cell lines established from a human individual who had inherited mutations in the DNA ligase I gene. The clinical symptoms of this DNA ligase I-deficient individual included growth retardation, lymphoma and immunodeficiency. Since cell lines established from this individual, which have 10-fold less DNA ligase I activity than control cell lines, also exhibit hypersensitivity to DNA damage introduced by ultra violet light, gamma irradiation and alkylating agents, it appears that DNA ligase I may also function in one or more DNA repair pathways. In this project we will elucidate the molecular mechanisms by which DNA ligase I participates in different DNA transactions. We hypothesize that, in vivo, DNA ligase I is recruited to its nicked DNA substrate by specific protein-protein interactions that are mediated by the amino terminal domain of this enzyme. This domain is not required for catalytic activity but is essential for in vivo function. In preliminary studies we have identified an interaction between DNA ligase I and proliferating cell nuclear antigen, a polypeptide that is required for DNA replication and is also involved DNA repair. Furthermore, in collaboration with Dr. Sam Wilson, we have identified an interaction between DNA ligase I and DNA polymerase beta within a multiprotein base excision repair complex. The functional consequences of these interactions will be examined by a combination of in vitro and in vivo studies. Since the N-terminal domain of DNA ligase I is phosphorylated in vivo, we will examine whether post-translational modification of this domain regulates the involvement of DNA ligase I in different DNA transactions. The long term goal of these studies is to understand the molecular mechanisms by which DNA ligase I functions in DNA replication and DNA repair. This will contribute to our knowledge of how the network of DNA metabolic pathways maintains genetic stability and will facilitate studies on the relationship between genetic instability and carcinogenesis.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM057479-03
Application #
6490188
Study Section
Chemical Pathology Study Section (CPA)
Program Officer
Wolfe, Paul B
Project Start
2000-01-01
Project End
2003-12-31
Budget Start
2002-01-01
Budget End
2002-12-31
Support Year
3
Fiscal Year
2002
Total Cost
$183,963
Indirect Cost
Name
University of Texas Health Science Center San Antonio
Department
Other Basic Sciences
Type
Schools of Medicine
DUNS #
800772162
City
San Antonio
State
TX
Country
United States
Zip Code
78229
Howes, Timothy R L; Sallmyr, Annahita; Brooks, Rhys et al. (2018) Erratum to ""Structure-activity relationships among DNA ligase inhibitors; characterization of a selective uncompetitive DNA ligase I inhibitor"" [DNA Repair 60C (2017) 29-39]. DNA Repair (Amst) 61:99
Sallmyr, Annahita; Tomkinson, Alan E (2018) Repair of DNA double-strand breaks by mammalian alternative end-joining pathways. J Biol Chem 293:10536-10546
Howes, Timothy R L; Sallmyr, Annahita; Brooks, Rhys et al. (2017) Structure-activity relationships among DNA ligase inhibitors: Characterization of a selective uncompetitive DNA ligase I inhibitor. DNA Repair (Amst) 60:29-39
Wiest, Nathaniel E; Tomkinson, Alan E (2017) Optimization of Native and Formaldehyde iPOND Techniques for Use in Suspension Cells. Methods Enzymol 591:1-32
Greco, George E; Matsumoto, Yoshihiro; Brooks, Rhys C et al. (2016) SCR7 is neither a selective nor a potent inhibitor of human DNA ligase IV. DNA Repair (Amst) 43:18-23
Slean, Meghan M; Panigrahi, Gagan B; Castel, Arturo López et al. (2016) Absence of MutS? leads to the formation of slipped-DNA for CTG/CAG contractions at primate replication forks. DNA Repair (Amst) 42:107-18
Peng, Zhimin; Liao, Zhongping; Matsumoto, Yoshihiro et al. (2016) Human DNA Ligase I Interacts with and Is Targeted for Degradation by the DCAF7 Specificity Factor of the Cul4-DDB1 Ubiquitin Ligase Complex. J Biol Chem 291:21893-21902
Hegde, Pavana M; Dutta, Arijit; Sengupta, Shiladitya et al. (2015) The C-terminal Domain (CTD) of Human DNA Glycosylase NEIL1 Is Required for Forming BERosome Repair Complex with DNA Replication Proteins at the Replicating Genome: DOMINANT NEGATIVE FUNCTION OF THE CTD. J Biol Chem 290:20919-33
Shanmugam, Ilanchezhian; Abbas, Mohammad; Ayoub, Farhan et al. (2014) Ubiquitin-specific peptidase 20 regulates Rad17 stability, checkpoint kinase 1 phosphorylation and DNA repair by homologous recombination. J Biol Chem 289:22739-48
Hegde, Muralidhar L; Hegde, Pavana M; Bellot, Larry J et al. (2013) Prereplicative repair of oxidized bases in the human genome is mediated by NEIL1 DNA glycosylase together with replication proteins. Proc Natl Acad Sci U S A 110:E3090-9

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