A highly basic KGKKGK sequence in the RNA-binding domain of the Cucumber necrosis virus coat protein is associated with encapsidation of full-length CNV RNA during infection |
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Authors: | Ron Reade D'Ann Rochon |
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Institution: | Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, Summerland, British Columbia, Canada V0H 1Z0 |
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Abstract: | The Cucumber necrosis virus particle is a T=3 icosahedron consisting of 180 identical coat protein (CP) subunits. The N-terminal 58 aa residue segment of the CP R domain is believed to bind viral RNA within virions and during assembly. We report results of in vivo experiments that examine the role of the R domain in assembly. Deletion analyses identified 3 conserved 5-10 aa regions as playing critical roles. A highly basic KGKKGK sequence was found to be both necessary and sufficient for encapsidation of the full-length genome and polymorphic virions were produced in mutants lacking the KGKKGK sequence. The amount of full-length RNA present in virions was substantially reduced in R domain mutants where 2 of the 4 lysine residues were substituted with alanine, whereas substitution of 4 lysines by arginine had only a modest effect. The potential role of the R domain in formation of a scaffold for particle assembly is discussed. |
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Keywords: | Cucumber necrosis virus Tomato bushy stunt virus Tombusvirus Coat protein Particle polymorphism Virus particle assembly Arginine rich motif Virus assembly scaffold |
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