Sandbox TMV

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 (2tmv)

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.

Repeating Subunits

Th repeating basic unit consists of 49 subunits which cover a section of 69 Å of height in three turns of the helix (= a rise of 23 Å per turn). A single strand of RNA is placed between the protein subunits at a distance of 40 Å from the outer diameter. The figure to the right depicts one basic unit. Protein and RNA are shown in spacefill mode, RNA in white, the protein changing from red to blue along the helix. The uppermoust subunit is marked light brown. Each protein subunit covers three nucleotides of the RNA

Repeating Subunits of Helical Tobacco Mosaic Virus

This section complements the article on Tobacco Mosaic Virus in the Molecule of the Month Series. See also Teaching Scenes, Tutorials, and Educators' Pages.

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.