Visualization of protein-nucleic acid interactions in a virus. Refined structure of intact Tobacco Mosaic Virus at 2.9 Angstroms resolution by X-ray fiber diffraction
Caspar Carboxylates
Two clusters of acidic amino acids are thought to be important for the disassembly of the . When the virus enters cells, the higher pH and lower calcium levels increase the repulsion of neighboring carboxylates, destabilizing the capsid. This concept was originally proposed by Caspar and subsequently examined by site-directed mutagenesis [1]. Several carboxylates were identified including , which contact each other in the helical stack (look closely at the in this lockwasher complex), and a cluster of four acidic amino acids, , near the center of the ring.
This section complements the article on Tobacco Mosaic Virus in the
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Publication Abstract from PubMed
The structure of tobacco mosaic virus (TMV) has been determined by fiber diffraction methods at 2.9 A resolution, and refined by restrained least-squares to an R-factor of 0.096. Protein-nucleic acid interactions are clearly visible. The final model contains all of the non-hydrogen atoms of the RNA and the protein, 71 water molecules, and two calcium-binding sites. Viral disassembly is driven by electrostatic repulsions between the charges in two carboxyl-carboxylate pairs and a phosphate-carboxylate pair. The phosphate-carboxylate pair and at least one of the carboxyl-carboxylate pairs appear to be calcium-binding sites. Nucleotide specificity, enabling TMV to recognize its own RNA by a repeating pattern of guanine residues, is provided by two guanine-specific hydrogen bonds in one of the three base-binding sites.
Visualization of protein-nucleic acid interactions in a virus. Refined structure of intact tobacco mosaic virus at 2.9 A resolution by X-ray fiber diffraction., Namba K, Pattanayek R, Stubbs G, J Mol Biol. 1989 Jul 20;208(2):307-25. PMID:2769760
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
About this Structure
2TMV is a 2 chains structure with sequences from Tobacco mosaic virus. The January 2009 RCSB PDB Molecule of the Month feature on Tobacco Mosaic Virus by David Goodsell is 10.2210/rcsb_pdb/mom_2009_1. Full crystallographic information is available from OCA.
References
Primary Reference
Visualization of protein-nucleic acid interactions in a virus. Refined structure of intact tobacco mosaic virus at 2.9 A resolution by X-ray fiber diffraction., Namba K, Pattanayek R, Stubbs G, J Mol Biol. 1989 Jul 20;208(2):307-25. PMID:2769760
Additional References
- ↑ Caspar carboxylates: the structural basis of tobamovirus assembly. Wang H, Planchart A, Stubbs G. Biophys. J. 1998, 74, 633-638.
