title: Phosphorylation of large T antigen regulates merkel cell polyomavirus replication.
abstract: Merkel Cell Polyomavirus (MCPyV) was recently discovered as a novel human polyomavirus that is associated with ~80% of Merkel Cell Carcinomas. The Large Tumor antigen (LT) is an early viral protein which has a variety of functions, including manipulation of the cell cycle and initiating viral DNA replication. Phosphorylation plays a critical regulatory role for polyomavirus LT proteins, but no investigation of MCPyV LT phosphorylation has been performed to date. In this report mass spectrometry analysis reveals three unique phosphorylation sites: T271, T297 and T299. In vivo replication assays confirm that phosphorylation of T271 does not play a role in viral replication, while modification at T297 and T299 have dramatic and opposing effects on LT's ability to initiate replication from the viral origin. We test these mutants for their ability to bind, unwind, and act as a functional helicase at the viral origin. These studies provide a framework for understanding how phosphorylation of LT may dynamically regulate viral replication. Although the natural host cell of MCPyV has not yet been established, this work provides a foundation for understanding how LT activity is regulated and provides tools for better exploring this regulation in both natural host cells and Merkel cells.
authors.affiliation: Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. jdia@mail.med.upenn.edu.
authors.forename: Jason
authors.initials: J
authors.lastname: Diaz
authors.affiliation: Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. wangxin2@mail.med.upenn.edu.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. sathw323@mail.med.upenn.edu.
authors.forename: Sabrina H
authors.initials: SH
authors.lastname: Tsang
authors.affiliation: Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA. jiaoj1@email.chop.edu.
authors.forename: Jing
authors.initials: J
authors.lastname: Jiao
authors.affiliation: Department of Microbiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. jianyou@mail.med.upenn.edu.
authors.forename: Jianxin
authors.initials: J
authors.lastname: You