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Basic Characteristics of Mutations
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Mutation Site
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S220A |
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Mutation Site Sentence
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Individual alanine substitution mutations at S147, S220, S239, and a double mutation (S220A/S239A) were engineered into the MCV-HF genome and transfected into 293 cells. |
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Mutation Level
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Amino acid level |
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Mutation Type
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Nonsynonymous substitution |
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Gene/Protein/Region
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Large T |
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Standardized Encoding Gene
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MCPyV_gp3
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Genotype/Subtype
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- |
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Viral Reference
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EU375804
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Functional Impact and Mechanisms
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Disease
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-
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Immune
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- |
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Target Gene
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FBXW7
BTRC
SKP2
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Clinical and Epidemiological Correlations
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Clinical Information
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- |
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Treatment
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- |
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Location
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- |
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Literature Information
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PMID
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28461484
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Title
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Protein-mediated viral latency is a novel mechanism for Merkel cell polyomavirus persistence
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Author
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Kwun HJ,Chang Y,Moore PS
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Journal
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Proceedings of the National Academy of Sciences of the United States of America
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Journal Info
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2017 May 16;114(20):E4040-E4047
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Abstract
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Viral latency, in which a virus genome does not replicate independently of the host cell genome and produces no infectious particles, is required for long-term virus persistence. There is no known latency mechanism for chronic small DNA virus infections. Merkel cell polyomavirus (MCV) causes an aggressive skin cancer after prolonged infection and requires an active large T (LT) phosphoprotein helicase to replicate. We show that evolutionarily conserved MCV LT phosphorylation sites are constitutively recognized by cellular Fbw7, betaTrCP, and Skp2 Skp-F-box-cullin (SCF) E3 ubiquitin ligases, which degrade and suppress steady-state LT protein levels. Knockdown of each of these E3 ligases enhances LT stability and promotes MCV genome replication. Mutations at two of these phosphoreceptor sites [serine (S)220 and S239] in the full viral genome increase LT levels and promote MCV virion production and transmission, which can be neutralized with anti-capsid antibody. Virus activation is not mediated by viral gene transactivation, given that these mutations do not increase late gene transcription in the absence of genome replication. Mechanistic target of rapamycin inhibition by either nutrient starvation or use of an active site inhibitor reduces Skp2 levels and stabilizes LT, leading to enhanced MCV replication and transmission. MCV can sense stresses in its intracellular environment, such as nutrient loss, through SCF E3 ligase activities, and responds by initiating active viral transmission. Protein-mediated viral latency through cellular SCF E3 ligase targeting of viral replication proteins is a unique form of latency that may promote chronic viral persistence for some small DNA and RNA viruses.
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Sequence Data
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-
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