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Albany 2019: 20th Conversation - Abstracts

Albany 2019
Conversation 20
June 11-15 2019
Adenine Press (2019)

Coordinated Actions of UvrA2 During Initiation of Nucleotide Excision Repair

Nucleotide excision repair (NER) protects genomic DNA from a large number of chemically diverse lesions, including nucleotide adducts and pyrimidine dimers. In bacteria, NER is initiated by UvrA2 or UvrA2 (B2) complex that scans DNA for changes in structure/dynamics. Once the complex encounters a potential damage site, UvrA2 dissociates, leaving UvrB to confirm lesion recognition and signal UvrC to nick the damaged strand for removal (Kisker, Kuper and van Houten, 2013). Each monomer in the UvrA2 dimer has two ATPase sites (proximal and distal), both of which are required for NER and are implicated in lesion recognition and loading of UvrB onto the DNA (Jaciuk et al., 2011 and Pakotiprapha et al., 2012). Our recent study of the UvrA2 ATPase kinetic mechanism revealed that the two sites exhibit asymmetric ATP binding and hydrolysis, which is modulated differentially by undamaged and damaged DNA. The findings suggest that key steps in the ATPase mechanism may be coupled to changes in UvrA2 interactions with DNA, ultimately leading to lesion recognition and UvrB loading (Case et al., 2019). We are now investigating the mechanochemical coupling between the ATPase reaction and other UvrA2 activities to determine how the nucleotide-bound state of UvrA2 influences its conformation and interactions with DNA. Preliminary results indicate the UvrA2 -lesion complex adopts a distinct conformation in the presence of ATP that is not observed with ADP or without any nucleotide. Additionally, analysis of Walker A and B mutants to prevent ATP binding or hydrolysis, respectively, is helping parse the role of each active site, and providing new insights into how UvrA2 uses ATP to recognize lesions and initiate NER.

References
    Case, B.C., Hartley, S., Osuga, M., Jeruzalmi, D. and Hingorani, M.M. (2019). The ATPase mechanism of UvrA2 reveals the distinct roles of proximal and distal ATPase sites in nucleotide excision repair. Nucleic Acids Res, under revision.

    Jaciuk, M., Nowak, E., Skowronek, K., Tanska, A. and Nowotny, M. (2011). Structure of UvrA nucleotide excision repair protein in complex with modified DNA. Nat Struct Mol Bio, 18, 191-197.

    Kisker, C., Kuper, J., and van Houten, B. (2013). Prokaryotic nucleotide excision repair. Cold Spring Harbor Perspect Biol, 5, a012591.

    Pakotiprapha, D., Samuels, M., Shen, K., Hu, J.H., and Jeruzalmi, D. (2012). Structure and mechanism of the UvrA-UvrB damage sensor. Nat Struct Mol Bio, 19, 291-298.

Brandon C. Case
Manju M. Hingorani*

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Brandon Case is a doctoral student of Prof. Manju Hingorani, and will provide short oral from the platform.

Department of Molecular Biology & Biochemistry
Wesleyan University
Middletown, CT 06459

*Email: mhingorani@wesleyan.edu
Phone: +(860) 685-2284