Dr. Sylvie Doublie
Structural Biology of DNA Replication and Repair
Modifications to DNA or RNA, as part of normal cellular processes or as aberrations, can have profound biological consequences. The major thrust of my research program is to study these nucleic acid modifications in the context of the enzymes and proteins that either generate or recognize them.
DNA polymerases, which otherwise faithfully replicate DNA, stumble when they encounter oxidative DNA lesions. Polymerases either will be blocked at the site of lesion, or bypass it. The latter case, referred to as translesion synthesis, may initiate an oncogenic process if the wrong base is inserted opposite the lesion. Uncovering the fundamental mechanisms underpinning translesion synthesis is paramount to understand the initial events of mutagenesis. Our work currently focuses on human DNA polymerases, including DNA polymerases beta and theta, which function in lesion repair or bypass respectively. We aim to elucidate at the atomic level how germline and somatic mutations affect polymerase function. We also seek to uncover how pol theta functions in double-strand break repair.
Several DNA repair mechanisms are in place to minimize damage in DNA before DNA polymerases replicate the genome. One of these processes is called Base Excision Repair (BER). The first step in BER is carried out by DNA glycosylases, so named because they hydrolyze the N-glycosidic bond between a damaged base and its deoxyribose, leaving an apurinic or apyrimidinic site in DNA. Our goal is to delineate the structural features of the human DNA glycosylases that are involved in recognition of DNA base damage produced by ionizing radiation. In particular, we intend to address the question of how enzymes with a similar active site architecture recognize vastly different substrates. Our focus is on human DNA glycosylases that repair oxidized lesions: the Nei-like enzymes (NEIL1-3), and Nth-like 1 NTHL1 glycosylase.
Crystal structure of human DNA polymerase theta
Crystal structure of mammalian NEIL3 DNA glycosylase
Zahn KE, Averill AM, Aller P, Wood RD, Doublie S. Human DNA polymerase theta grasps the primer terminus to mediate DNA repair. Nat Struct Mol Biol. 2015 Apr;22(4):304-11
Eckenroth BE, Fleming AM, Sweasy JB, Burrows CJ, Doublie S. Crystal structure of DNA polymerase beta with DNA containing the base lesion spiroiminodihydantoin in a templating position. Biochemistry. 2014 Apr 8;53(13):2075-7
Liu M, Imamura K, Averill AM, Wallace SS, Doublie S. Structural characterization of a mouse ortholog of human NEIL3 with a marked preference for single-stranded DNA. Structure. 2013 Feb 5;21(2):247-56
Yang Q, Coseno M, Gilmartin GM, Doublie S. Crystal structure of a human cleavage factor CFI(m)25/CFI(m)68/RNA complex provides an insight into poly(A) site recognition and RNA looping. Structure. 2011 Mar 9;19(3):368-77.
Hyde SJ, Eckenroth BE, Smith BA, Eberley WA, Heintz NH, Jackman JE, Doublie S. tRNAHis guanylyltransferase (THG1), a unique 3′-5′ nucleotidyl transferase, shares unexpected structural homology with canonical 5′-3′ DNA polymerases. Proc Natl Acad Sci U S A. 2010 Nov 23;107(47):20305-10