• Login
    View Item 
    •   Home
    • University of Alaska Fairbanks
    • UAF Graduate School
    • Biological Sciences
    • View Item
    •   Home
    • University of Alaska Fairbanks
    • UAF Graduate School
    • Biological Sciences
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of Scholarworks@UACommunitiesPublication DateAuthorsTitlesSubjectsTypeThis CollectionPublication DateAuthorsTitlesSubjectsType

    My Account

    Login

    First Time Submitters, Register Here

    Register

    Statistics

    Display statistics

    Mammalian mismatch repair: hotspots and protein complexes

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Thumbnail
    Name:
    Matton.Nancy.2000.pdf
    Size:
    2.409Mb
    Format:
    PDF
    Download
    Author
    Matton, Nancy
    Keyword
    DNA repair
    DNA damage
    Mutagenesis
    Metadata
    Show full item record
    URI
    http://hdl.handle.net/11122/5030
    Abstract
    Deficiencies in DNA mismatch repair have been found in hereditary cancers as well as in sporadic cancers, illustrating the importance of mismatch repair in maintaining genomic integrity. To determine if inefficient mismatch repair can contribute to hotspots of mutation, repair rates were determined 'in vivo' in mammalian cells for mismatched nucleotides located at H-ras codon 10 and compared to previously determined repair rates at a nearby activating hotspot of mutation, H-ras codon 12. Repair rates for H-ras codon 10 are significantly improved over repair rates at codon 12. This indicates that inefficiencies in mismatch repair are responsible, at least in part, for the well-documented hotspot of mutation at codon 12 and that surrounding sequence context can effect repair of mismatches. Gel-shift analysis demonstrates that the degree of binding by the initial mismatch recognition factor hMutS[alpha] (heterodimer of hMSH6 and hMSH2) correlates with 'in vivo' repair rates for each mismatch tested at the codon 12 location. UV cross-linking of nuclear proteins to G:A and G:T mismatches at codon 10 or codon 12 generally confirm these results. Overall this suggests that there is lowered efficiency in the kinetics of mismatch repair at codon 12, perhaps in the initiation step, rather than innaccurate repair leading to mutation. The interactions of specific mismatch repair proteins in human nuclear extracts were then examined to determine the proteins binding to mismatched DNA. Immunoprecipitation followed by Western blotting indicates two novel complexes that exist in the absence of ATP: one consisting of hMSH2, hMSH6, hMLH1 and hPMS2 and the other consisting of hMSH2, hMSH6, hMLH1 and hPMS1. Furthermore, the protein complexes specifically bind to mismatched DNA and not to a similar homoduplex oligonucleotide. The protein complex-DNA interactions occur primarily through hMSH6, although hMSH2 can also become cross-linked to the mismatched substrate. In the presence of ATP, the binding of hMSH6 to mismatched DNA is decreased. In addition, hMLH1, hPMS2 and hPMS1 no longer interact with each other or with the hMutS[alpha] complex. However, the ability of hMLH1 to co-immunoprecipitate mismatched DNA 'increases' in the presence of ATP, suggesting a role for hMLH1 in subsequent ATP-dependent repair processes.
    Description
    Dissertation (Ph.D.) University of Alaska Fairbanks, 2000
    Date
    2000-05
    Type
    Dissertation
    Collections
    Biological Sciences

    entitlement

     
    ABOUT US|HELP|BROWSE|ADVANCED SEARCH

    The University of Alaska is an affirmative action/equal opportunity employer, educational institution and provider and prohibits illegal discrimination against any individual.

    Learn more about UA’s notice of nondiscrimination.

    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.