Structural studies on tobacco streak virus coat protein: Insights into the pleomorphic nature of ilarviruses

Gulati, Ashutosh and Alapati, Kavitha and Murthy, Abhinandan and Savithri, HS and Murthy, MRN (2016) Structural studies on tobacco streak virus coat protein: Insights into the pleomorphic nature of ilarviruses. In: JOURNAL OF STRUCTURAL BIOLOGY, 193 (2). pp. 95-105.

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Abstract

Tobacco streak virus (TSV), the type member of Ilarvirus genus, is a major plant pathogen. TSV purified from infected plants consists of a ss-RNA genome encapsidated in spheroidal particles with diameters of 27, 30 and 33 nm constructed from multiple copies of a single species of coat protein (CP) subunits. Apart from protecting the viral genome, CPs of ilarviruses play several key roles in the life cycle of these viruses. Unlike the related bromo and cucumoviruses, ilarvirus particles are labile and pleomorphic, which has posed difficulties in their crystallization and structure determination. In the current study, a truncated TSV-CP was crystallized in two distinct forms and their structures were determined at resolutions of 2.4 angstrom and 2.1 angstrom, respectively. The core of TSV CP was found to possess the canonical beta-barrel jelly roll tertiary structure observed in several other viruses. Dimers of CP with swapped C-terminal arms (C-arm) were observed in both the crystal forms. The C-arm was found to be flexible and is likely to be responsible for the polymorphic and pleomorphic nature of TSV capsids. Consistent with this observation, mutations in the hinge region of the C-arm that reduce the flexibility resulted in the formation of more uniform particles. TSV CP was found to be structurally similar to that of Alfalfa mosaic virus (AMV) accounting for similar mechanism of genome activation in alfamo and ilar viruses. This communication represents the first report on the structure of the CP from an ilarvirus. (C) 2015 Elsevier Inc. All rights reserved.

Item Type:	Journal Article
Publication:	JOURNAL OF STRUCTURAL BIOLOGY
Publisher:	ACADEMIC PRESS INC ELSEVIER SCIENCE
Additional Information:	Copy right for this article belongs to the ACADEMIC PRESS INC ELSEVIER SCIENCE, 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA
Keywords:	Tobacco streak virus; Coat protein; Capsid assembly; X-ray crystallography; Viral pleomorphism
Department/Centre:	Division of Biological Sciences > Biochemistry Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	17 Mar 2016 04:40
Last Modified:	17 Mar 2016 04:40
URI:	http://eprints.iisc.ac.in/id/eprint/53308

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