title: The minimum replication origin of merkel cell polyomavirus has a unique large T-antigen loading architecture and requires small T-antigen expression for optimal replication.
abstract: Merkel cell polyomavirus (MCV) is a recently discovered human polyomavirus causing the majority of human Merkel cell carcinomas. We mapped a 71-bp minimal MCV replication core origin sufficient for initiating eukaryotic DNA replication in the presence of wild-type MCV large T protein (LT). The origin includes a poly(T)-rich tract and eight variably oriented, GAGGC-like pentanucleotide sequences (PS) that serve as LT recognition sites. Mutation analysis shows that only four of the eight PS are required for origin replication. A single point mutation in one origin PS from a naturally occurring, tumor-derived virus reduces LT assembly on the origin and eliminates viral DNA replication. Tumor-derived LT having mutations truncating either the origin-binding domain or the helicase domain also prevent LT-origin assembly. Optimal MCV replication requires coexpression of MCV small T protein (sT), together with LT. An intact DnaJ domain on the LT is required for replication but is dispensable on the sT. In contrast, PP2A targeting by sT is required for enhanced replication. The MCV origin provides a novel model for eukaryotic replication from a defined DNA element and illustrates the selective pressure within tumors to abrogate independent MCV replication.
authors.affiliation: Molecular Virology Program, University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Hyun Jin
authors.initials: HJ
authors.lastname: Kwun
authors.forename: Anna
authors.initials: A
authors.lastname: Guastafierro
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shuda
authors.forename: Gretchen
authors.initials: G
authors.lastname: Meinke
authors.forename: Andrew
authors.initials: A
authors.lastname: Bohm
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Moore
authors.forename: Yuan
authors.initials: Y
authors.lastname: Chang
mesh_terms: D000957:Antigens, Viral, Tumor / Q000502:physiology*; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D006801:Humans; D018862:Merkel Cells / Q000821:virology*; D008969:Molecular Sequence Data; D017354:Point Mutation; D011120:Polyomavirus / Q000235:genetics / Q000502:physiology*; D011485:Protein Binding; D018741:Replication Origin / Q000235:genetics*; D014779:Virus Replication
chemical_list: D000957:Antigens, Viral, Tumor; D004279:DNA, Viral