The structure of tobacco ringspot virus: a link in the evolution of icosahedral capsids in the picornavirus superfamily
| Autor: | John E. Johnson, Veda Chandrasekar |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Models
Molecular Picornavirus Protein Conformation viruses Molecular Sequence Data Nepovirus Sequence alignment Picornaviridae Crystallography X-Ray Conserved sequence Evolution Molecular viral evolution 03 medical and health sciences Protein structure Capsid Structural Biology tobacco ringspot virus Amino Acid Sequence Molecular Biology Conserved Sequence 030304 developmental biology 0303 health sciences biology nematode transmission 030302 biochemistry & molecular biology comovirus biochemical phenomena metabolism and nutrition biology.organism_classification Virology Protein Structure Tertiary picornavirus Viral evolution Tobacco ringspot virus Sequence Alignment |
| Zdroj: | Structure (London, England : 1993). 6(2) |
| ISSN: | 0969-2126 |
| Popis: | Background: Tobacco ringspot virus (TRSV) is a member of the nepovirus genus of icosahedral RNA plant viruses that cause disease in fruit crops. Nepoviruses, comoviruses and picornaviruses are classified in the picornavirus superfamily. Crystal structures of comoviruses and picornaviruses and the molecular mass of the TRSV subunit (sufficient to accommodate three β -barrel domains) suggested that nepoviruses may represent a link in the evolution of the picornavirus capsids from a T=3 icosahedral virus. This evolutionary process is thought to involve triplication of the capsid protein gene, to encode a three-domain polyprotein, followed by development of cleavage sites in the interdomain linking regions. Structural studies on TRSV were initiated to determine if the TRSV subunit corresponds to the proposed uncleaved three domain polyprotein. Results: The 3.5 a resolution structure of TRSV shows that the capsid protein consists of three β -barrel domains covalently linked by extended polypeptides. The order of connectivity of the domains in TRSV confirms the proposed connectivity for the precleaved comovirus and picornavirus capsid polyprotein. Structural differences between equivalent domains in TRSV and comoviruses are confined to the external surface loops, interdomain connecting polypeptides and N termini. The three different domains within TRSV and comoviruses are more closely related at the structural level than the three individual domains within picornaviruses. Conclusions: The structural results confirm the notion of divergent evolution of the capsid polyproteins of nepoviruses, comoviruses and picornaviruses from a common ancestor. A number of residues were found to be conserved among various nepoviruses, some of which stabilize the quaternary structure of the three domains in the TRSV capsid protein subunit. Two conserved regions were identified on the external surface of TRSV, however, mutational studies will be needed to understand their functional significance. Nepoviruses transmitted by the same nematode species do not share regions with similar amino acid composition on the viral surface. |
| Databáze: | OpenAIRE |
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