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Functional significance of the physical interaction between the herpes simplex virus type 1 origin-binding protein, UL9, and the DNA polymerase processivity factor, UL42

Trego, Kelly S
http://rave.ohiolink.edu/etdc/view?acc_num=osu1061240569

Abstract Details

2003, Doctor of Philosophy, Ohio State University, Molecular Genetics.
The origin (ori)-binding protein of herpes simplex virus type 1 (HSV-1), encoded by the UL9 open-reading frame, has been shown to physically interact with a number of cellular and viral proteins, including three HSV-1 proteins (ICP8, UL42, and UL8) essential for ori-dependent DNA replication. In this report, it is demonstrated for the first time that the DNA polymerase processivity factor, UL42 protein, provides accessory function to the UL9 protein, by enhancing the 3' to 5' helicase activity of UL9 on partially duplex non-specific DNA substrates. UL42 fails to enhance the unwinding activity of a non-cognate helicase, suggesting enhancement of unwinding requires the physical interaction between UL42 and UL9. UL42 increases the steady-state rate for unwinding a 23/38-mer by UL9, but only at limiting UL9 concentrations, consistent with a role in increasing the affinity of UL9 for DNA. Optimum enhancement of unwinding was observed at UL42:UL9 molecular ratios of 4:1, although enhancement was reduced when high ratios of UL42:DNA were present. Under the assay conditions employed, UL42 did not alter the rate of dissociation of UL9 from the DNA substrate. UL42 also did not alter the requirement or time for an assembly/conformational change step, regardless of whether it was added to DNA prior to or at the same time as UL9, or after steady-state unwinding by UL9 alone had been achieved. Thus, the increased affinity of UL9 for DNA most likely is the result of an increase in the association rate constant for binding of UL9 to DNA, and explains why helicase enhancement is observed only at subsaturating concentrations of UL9 with respect to DNA. Consistent with this interpretation are results which demonstrate that UL42 also enhances the ATPase activity of UL9 on single-strand and partially duplex DNA substrates when UL9 is limiting. In contrast, ICP8 enhances unwinding at both saturating and subsaturating UL9 concentrations, and reduces or eliminates the lag period. The different means by which ICP8 and UL42 enhance activities of UL9 suggest that these two members of the presumed functional replisome may act synergistically on UL9 to effect initiation of HSV-1 DNA replication in vivo.
Deborah Parris (Advisor)
196 p.
UL9; UL42; herpes simplex virus type 1

Recommended Citations

Citations

  • Trego, K. S. (2003). Functional significance of the physical interaction between the herpes simplex virus type 1 origin-binding protein, UL9, and the DNA polymerase processivity factor, UL42 [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1061240569

    APA Style (7th edition)

  • Trego, Kelly. Functional significance of the physical interaction between the herpes simplex virus type 1 origin-binding protein, UL9, and the DNA polymerase processivity factor, UL42. 2003. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1061240569.

    MLA Style (8th edition)

  • Trego, Kelly. "Functional significance of the physical interaction between the herpes simplex virus type 1 origin-binding protein, UL9, and the DNA polymerase processivity factor, UL42." Doctoral dissertation, Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1061240569

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.