Interaction of an accessory protein with DNA polymerase alpha /
DNA polymerase alpha (pol []) is an essential protein required for the initiation of eukaryotic DNA replication (synthesis). Alpha accessory protein ([]AP) has been reported to stimulate DNA synthesis by pol []. The accessory protein binds single- and doublestranded DNA (dsDNA), unwinds dsDNA, and...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739669001&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | DNA polymerase alpha (pol []) is an essential protein required for the initiation of eukaryotic DNA replication (synthesis). Alpha accessory protein ([]AP) has been reported to stimulate DNA synthesis by pol []. The accessory protein binds single- and doublestranded DNA (dsDNA), unwinds dsDNA, and interferes with DNA synthesis repressor protein, retinoblastoma protein. As an organism ages, the capacity to initiate DNA replication declines. Alpha AP interacted with pol [] to overcome the age-related decline in DNA synthesis capacity. Pol [] from the livers of aging mice had a decreased tendency co-purify with []AP. If pol [] copurified with []AP or another dsDNA helicase (TAg), exogenous []AP was not able to stimulate DNA synthesis initiation, indicating the possibility that there was a limit to the number of []AP molecules able to interact with pol []. We examined this phenomenon with binding studies utilizing a fragment of dsDNA containing the Simian virus 40 (SV40) origin of replication. We showed that []AP was able to bind this fragment with a Km of 2.3 ng/[]l[]AP. Pol [] was not able to bind this dsDNA fragment in the absence of []AP but in the presence of []AP, the Km for pol [] binding was 15 ng/[]l pol []. If pol [] was present in amounts less than 15 ng/[]l, the stimulation of DNA synthesis by 1.7 ng/[]l []AP was greater than at higher levels of pol []. If []AP was present in amounts less than 2.3 ng/[]l, the initiation of DNA synthesis by 12 ng/[]l pol [] occurred at a greater rate than if higher levels of []AP were present. Thus, maximal interaction between pol [] and [] occurred at concentrations close to or below the respective Km's for binding. At higher levels of either protein, DNA synthesis rates were less than optimal. The data suggest that excess []AP might prepare too many pol [] binding sites, or, conversely, excess pol [] might not have enough binding sites to initiate replication at maximal levels. |
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| Item Description: | Vita. "Major Subject: Veterinary Anatomy". |
| Physical Description: | xi, 133 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 117-128. |