1zdh: Difference between revisions

[[Image:1zdh.gif|left|200px]]<br /><applet load="1zdh" size="350" color="white" frame="true" align="right" spinBox="true"  

Crystal structures of two complexes between recombinant MS2 capsids and RNA operator fragments have been determined at 2.7 A resolution. The coat protein of the RNA bacteriophage MS2 is bifunctional; it forms the icosahedral virus shell to protect the viral nucleic acid and it acts as a translational repressor by binding with high specificity to a unique site on the RNA, a single stem-loop structure, containing the initiation codon of the gene for the viral replicase. In order to determine the structure of these protein-RNA complexes, we have used chemically synthesized variants of the stem-loop fragment and soaked them into crystals of recombinant capsids. The RNA stem-loop, as bound to the protein, forms a crescent-like structure and interacts with the surface of the beta-sheet of a coat protein dimer. It makes protein contacts with seven phosphate groups on the 5' side of the stem-loop, with a pyrimidine base at position -5, which stacks onto a tyrosine, and with two exposed adenine bases, one in the loop and one at a bulge in the stem. Replacement of the wild-type uridine with a cytosine at position -5 increases the affinity of the RNA to the dimer significantly. The complex with RNA stem-loop having cytosine at this position differs from that of the wild-type complex mainly by having one extra intramolecular RNA interaction and one extra water-mediated hydrogen bond.

1ZDH 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]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ZDH OCA].  

[[Category: K Valegard,S Van Den Worm,L Liljas]]

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