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Susan F. Cotmore, PhD
Senior Research Scientist, Laboratory Medicine

CB 408
203-785-5495
susan.cotmore@yale.edu

1969; B.Sc.; University of Bristol, England.
1973; Ph.D.; University of London, England.
Fellowship: University College London; Imperial Cancer Research Fund; Yale University

Community of Science Biosketch

Research Interests
Parvoviruses are among the smallest of the known viruses, encoding just two genes, and yet they rapidly take over their mammalian host cell, evading its normal cell cycle checkpoint controls and reprogramming its synthetic machinery for maximal progeny virus production. These viruses are unique in having single-stranded, linear, DNA genomes which are amplified by an unusual unidirectional, leading-strand specific, mode of DNA replication dubbed rolling hairpin synthesis, carried out primarily by the host cell machinery but aided and abetted by a single, pleiotropic, virally-coded nuclear phospho-protein, NS1. NS1, a site-specific nickase, initiates DNA synthesis by introducing a single-strand nick into specific origin sequences, becoming covalently-attached to the 5' end of the DNA at the nick site and providing a 3' hydroxyl to prime subsequent DNA synthesis by a host polymerase. Parvoviruses have hairpin telomeres that sequentially unfold and refold to shuttle the ensuing replication fork back and forth along the linear genome, creating a continuous, multimeric DNA strand which is then cut into unit-length genomes by NS1. We have concentrated on defining the DNA sequence elements required in cis for the correct functioning of the viral origins. We have identified high-affinity binding sites for NS1, and the initiation site at which NS1 nicks and becomes covalently attached to the DNA. Although these site are arranged so that NS1 projects over the nick site, it is not able to cleave the DNA strand unless this complex is activated by the juxtaposition of a specific cellular DNA-binding protein. Thus in each origin there are also unique sequences and spacer elements which allow these cellular DNA-binding proteins to bind into the origin at the precise position needed to activate NS1.

In the right-hand (5') MVM hairpin, we have characterized a HeLa cell factor that is absolutely required to allow NS1 to nick the origin, and shown it to be a member of the high mobility group, non-histone chromosomal proteins belonging to the HMG1/2 family. HMG1/2 proteins are expressed at high copy number in all eukaryotic cells and bind both single-stranded and double-stranded DNA with low affinity, and with little or no specificity for any target DNA sequence. Instead they form complexes with a variety of other site-specific DNA binding proteins, including NS1, which deliver them to particular sites in the DNA. Here they bind exclusively into the minor groove of the helix, distorting the groove and severely bending the DNA. Although the right-hand origin contains an essential NS1 binding site which positions the initiator over the nick site, it also contains other candidate NS1 binding sites, and we have shown that one of these, positioned some 120 bases from the nick site, is essential for initiation. Protein footprinting techniques show that in the presence of HMG1, NS1 molecules positioned at the two critical sites are able to interact in a way which generates a double helical loop at a specific site in the intervening DNA sequence, allowing the assembly of a precise three-dimensional complex, the nickosome, in which the NS1 nickase activity is unmasked. We are currently using mutational analysis of the telomere in an attempt to define precisely how NS1 and HMG interact with the DNA to create this structure.

Publications

Cotmore, S.F., Gottlieb, R.L. and Tattersall, P.  Replication initiator protein NS1 of parvovirus MVM binds to modular divergent sites distributed throughout duplex viral DNA.  J. Virol. In press, 2007.

Cotmore, S.F. and Tattersall, P.  Parvoviral host range and cell entry mechanisms.  Advances in Virus Research, 70, Ch 5, 183-232, 2007

Burnett, E., Cotmore, S.F., & Tattersall, P. Segregation of a single outboard left-end origin is essential for the viability of parvovirus Minute Virus of Mice. J. Virol., 80:10879-83, 2006.

Farr, G., Cotmore, S.F. & Tattersall, P.  VP2 cleavage and a leucine ring at the base of the five-fold cylinder control pH-dependent externalization of both the VP1 N-terminus and the genome of Minute Virus of Mice. J. Virol., 80:161–171, 2006.

Kerr, J.R., Cotmore, S.F., Bloom, M.E., Linden, R.M., & Parrish, C.R. eds. “Parvoviruses.” Edward Arnold Publishers Ltd., London, 2006.

Cotmore S.F. & Tattersall P. Parvoviruses. Chapter 29 in "DNA replication and Human Disease".  DePamphilis M., ed. Cold Spring Harbor Laboratory Press.  Cold Spring Harbor, New York. pp 593-608, 2006.

Cotmore S.F. & Tattersall P.  Genome Structure and Organization.  Chapter 7 in “Parvoviruses.” Kerr, J.R., Cotmore, S.F., Bloom, M.E., Linden, R.M., & Parrish, C.R. eds.  Edward Arnold Ltd., London, pp 73-94, 2006.

Cotmore, S. F. & Tattersall, P.   A rolling hairpin strategy: basic mechanisms of DNA replication in the parvoviruses. Chapter 14, in "The Parvoviruses", Kerr, J., Cotmore, S.F., Bloom, M.E., Linden, R.M., & Parrish, C.R., eds., Hodder Arnold, London, pp. 171-188, 2006.

D’Abramo Jr., A. M., Ali, A. A., Wang, F., Cotmore, S.F. & Tattersall, P.  Host range mutants of Minute Virus of Mice with a single VP2 amino acid change require additional silent mutations that regulate NS2 accumulation.  Virology, 340:143-154, 2005.

Cotmore, S. F. & Tattersall, P.  Encapsidation of Minute Virus of Mice DNA: aspects of the translocation mechanism revealed by the structure of partially-packaged genomes. Virology, 336:100-112, 2005.

Cotmore, S. F. & Tattersall, P.  Packaging sense is controlled by the efficiency of the nick site in the right-end replication origin of parvoviruses MVM and LuIII.  J. Virol., 79:2287-300, 2005.

Tattersall, P. & Cotmore, S. F.   The Parvoviruses.   Chapter 21 in Topley and Wilson's Microbiology and Microbial Infections. 10th edition - Virology, Vol I, Mahy, B.W.J. & ter Meulen, V., eds., Hodder Arnold, London, pp.  407-438, 2005.