Molecular biology study of satellite panicum mosaic virus capsid protein

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Title: Molecular biology study of satellite panicum mosaic virus capsid protein
Author: Qi, Dong
Abstract: Satellite panicum mosaic virus (SPMV ) depends on its helper Panicum mosaic virus (PMV ) for replication and movement in host plants . The positive -sense single -stranded genomic RNA of SPMV encodes a 17 -kDa capsid protein (CP ) to form 16 -nm virions . Previous studies showed that SPMV CP has multiple functions during infection including encapsidation , symptom exacerbation , inhibiting the accumulation of SPMV DIs , and facilitating systemic movement . This dissertation confirms and extends the results of our previous reports with new biological and biochemical evidence . For example , the dosage effect of SPMV CP on symptom severity supports its function as a pathogenicity factor . Biological assays also demonstrate compensatory effects of SPMV CP on virus mutants defective in systemic movement . In addition , it is shown for the first time that SPMV CP is involved in cellto - cell movement of SPMV RNA and associated with the cell wall and membranes , a signature property of plant virus movement proteins . However , SPMV CP in the cytosol exists exclusively as virions and is dispensable for symptom exacerbation . SPMV CP contains a distinctive N -terminal arginine -rich motif (N -ARM ) , which is required for the in vitro binding of SPMV and PMV genomic RNAs by SPMV CP . Mutations of this region impair all known functions of SPMV CP . Interestingly , manipulation of the C -terminus of SPMV CP resulted in the same phenotypes as alterations in the N -ARM except that this does not affect the RNA binding activity of SPMV CP . Biological experiments demonstrate that virions are not required for the properties of SPMV CP to facilitate local and systemic movement and inhibit the accumulation of SPMV DIs , suggesting that SPMV CP and RNA form alternative complexes for these purposes . This dissertation study reveals the nucleolar localization of SPMV CP and its interaction with PMV CP in the form of virions . The identification of distinct functional domains of SPMV CP and its complex subcellular localization profile resulted in the proposal of a tentative model on how the functions of SPMV CP are coordinated for a robust infection . This dissertation provides a foundation for further understanding of the complex interactions among host plants , helper viruses , and satellites .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2584
Date: 2009-05-15

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Molecular biology study of satellite panicum mosaic virus capsid protein. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2584 .

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