2ms2: Difference between revisions

[[Image:2ms2.gif|left|200px]]<br /><applet load="2ms2" size="350" color="white" frame="true" align="right" spinBox="true"  

Bacteriophage MS2 is an icosahedral virus with 180 copies of a coat protein forming a shell around a single-stranded RNA molecule. The coat protein subunits form a lattice with the triangulation number T = 3. The coat protein has a fold which is different from the fold of all other viral coat proteins so far known. It consists of a five-stranded beta sheet facing the inside of the particle, and a hairpin and two helices on the outside. The crystal structure has been refined at 2.8 A resolution. The final R-factor was 0.189 for reflections with F &gt; 2 sigma, and the root-mean-square deviation from idealized bond lengths and bond angles was 0.015 A and 2.9 degrees, respectively. The three chemically identical conformers A, B and C are largely similar. The B conformer has a unique conformation in one loop, which is involved in 5-fold interactions, while the A and C conformers, which are involved in the quasi-6-fold contacts, are similar throughout the structure. One cis-proline has been identified in the B conformer but the corresponding prolines in A and C are of the trans isomer. This residue is conserved within small RNA coliphages and it is proposed that this isomerization enables a less elongated loop (FG) around the 5-fold axis, thus creating a channel. The extensive dimer contact supports the idea of dimers as initial building blocks. An assembly pathway is proposed where five dimers converge into a pentamer and 12 pentamers are linked together with free dimers creating a complete particle.

2MS2 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Enterobacterio_phage_ms2 Enterobacterio phage ms2]. This structure supersedes the now removed PDB entry 1MS2. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2MS2 OCA].  

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