Advanced Search
DSpace@MIT

The versatile E. coli adaptive response protein AlkB mitigates toxicity and mutagenicity of etheno-, ethano-, and methyl-modified bases in vivo

Research and Teaching Output of the MIT Community

Show simple item record

dc.contributor.advisor John M. Essigmann. en_US
dc.contributor.author Frick, Lauren Elizabeth en_US
dc.contributor.other Massachusetts Institute of Technology. Biological Engineering Division. en_US
dc.date.accessioned 2009-01-23T14:57:36Z
dc.date.available 2009-01-23T14:57:36Z
dc.date.copyright 2007 en_US
dc.date.issued 2007 en_US
dc.identifier.uri http://dspace.mit.edu/handle/1721.1/42382 en_US
dc.identifier.uri http://hdl.handle.net/1721.1/42382
dc.description Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2007. en_US
dc.description Vita. en_US
dc.description Includes bibliographical references. en_US
dc.description.abstract The Escherichia coli AlkB protein is an exceptionally versatile DNA repair enzyme. Its expression is induced upon exposure to alkylating agents as part of the Ada-mediated adaptive response. This member of the ac-ketoglutarate/iron(II)-dependent dioxygenase family was originally discovered to reverse directly methylated lesions formed preferentially in single-stranded regions of DNA, such as 1-methyladenine and 3- methylcytosine. Repair proceeds via an oxidative demethylation pathway, in which the aberrant methyl group is hydroxylated and spontaneously lost as formaldehyde. Since these early studies, the list of lesions repaired by AlkB through this pathway has been extended to include 1-methylguanine, 3-methylthymine, 3-ethylcytosine, and 1-ethyladenine. Furthermore, the protein possesses a second, distinct chemical mechanism through which it can repair another class of lesions, the etheno-adducts formed by the reaction of DNA with metabolites of the carcinogen vinyl chloride or with breakdown products generated by lipid oxidation. In this case, direct repair proceeds through epoxidation of the etheno bond, creating an intermediate that hydrolyzes to a glycol form and finally releases the two-carbon bridge as glyoxal, restoring the unadducted adenine or cytosine. Thus, the AlkB protein bridges the repair of alkylative lesions with those induced by oxidative stress and embodies the multi-faceted protection required to preserve genomic stability and coding information despite the constant threats to which organisms are exposed. en_US
dc.description.abstract (cont.) Herein, we exploit and characterize a pair of E. coli strains differing only in AlkB status to demonstrate the ability of AlkB to repair the etheno-lesions, the structural analog 1,N6-ethanoadenine (EA), and 3-methyluracil in vivo. Additionally, we establish the ability of the EA "repair product" to form interstrand cross-links in certain sequence contexts of duplex DNA. We also show that although the adaptive response proteins repair lesions generated by oxidative stress, oxidative agents do not induce expression of the response. Finally, we establish that certain hypothesized substrates for AlkB are not in fact repaired by the enzyme, nor are they repaired by another adaptive response protein, AidB. This work extends the current knowledge regarding the amazing ability of AlkB to protect cellular nucleic acids from damage arising from a diverse array of both endogenous and exogenous sources. en_US
dc.description.statementofresponsibility by Lauren Elizabeth Frick. en_US
dc.format.extent 258 p. en_US
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri http://dspace.mit.edu/handle/1721.1/42382 en_US
dc.rights.uri http://dspace.mit.edu/handle/1721.1/7582 en_US
dc.subject Biological Engineering Division. en_US
dc.title The versatile E. coli adaptive response protein AlkB mitigates toxicity and mutagenicity of etheno-, ethano-, and methyl-modified bases in vivo en_US
dc.title.alternative Versatile Escherichia coli adaptive response protein AlkB mitigates toxicity and mutagenicity of etheno-, ethano-, and methyl- modified bases in vivo en_US
dc.type Thesis en_US
dc.description.degree Ph.D. en_US
dc.contributor.department Massachusetts Institute of Technology. Biological Engineering Division. en_US
dc.identifier.oclc 234446098 en_US


Files in this item

Name Size Format Description
234446098.pdf 20.01Mb PDF Preview, non-printable (open to all)
234446098-MIT.pdf 20.01Mb PDF Full printable version (MIT only)

This item appears in the following Collection(s)

Show simple item record

MIT-Mirage