Identification of an elicitor active site within the three-dimensional structure of the tobacco mosaic tobamovirus coat protein.

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TitleIdentification of an elicitor active site within the three-dimensional structure of the tobacco mosaic tobamovirus coat protein.
Publication TypeJournal Article
Year of Publication1996
AuthorsTaraporewala, ZF, Culver, JN
JournalPlant Cell
Volume8
Issue2
Pagination169-78
Date Published1996 Feb
ISSN1040-4651
KeywordsAmino Acid Sequence, Binding Sites, Capsid, Computer Simulation, Conserved Sequence, Models, Molecular, Molecular Sequence Data, Mutagenesis, Site-Directed, Plants, Toxic, Point Mutation, Protein Conformation, Protein Structure, Secondary, Recombinant Proteins, Sequence Deletion, Tobacco, Tobamovirus
Abstract

The coat protein (CP) of tobacco mosaic tobamovirus (TMV) elicits the hypersensitive response (HR) conferred by the N' gene from Nicotiana sylvestris. This study presents evidence demonstrating a critical role for a specific CP structural site in eliciting this HR. Based on the known structure of the TMV CP, specific substitutions were created within the CP of the elicitor strain P20L to identify structural areas essential for host recognition. Of 32 substitutions made, 14 conferred either a temperature-sensitive (loss of the HR at 29 degrees C) or a knockout (loss of the HR at 25 degrees C) HR phenotype in N.sylvestris. These essential residues were noncontiguous in position; however, within the three-dimensional CP structure, all resided primarily along the right face of the molecule's helical bundle. Substitutions that did not affect the HR phenotype either were located outside of this area or were conservative in change. In addition, placing two temperature-sensitive substitutions within the same CP resulted in lowering temperature sensitivity from 29 to 27 degrees C. This additive effect suggests that residues essential for HR elicitation contribute independently to host recognition. This feature is characteristic of recognition surfaces. The presence of a specific elicitor active site within the three-dimensional structure of the TMV CP is consistent with binding of a host-encoded receptor and demonstrates the importance of CP structure in HR specificity.

DOI10.1105/tpc.8.2.169
Alternate JournalPlant Cell
PubMed ID8742708
PubMed Central IDPMC161089