View source for 1evx

[[Image:1evx.gif|left|200px]]<br /><applet load="1evx" size="450" color="white" frame="true" align="right" spinBox="true" 
caption="1evx, resolution 2.0&Aring;" />
'''APO CRYSTAL STRUCTURE OF THE HOMING ENDONUCLEASE, I-PPOI'''<br />

==Overview==
The homing endonuclease I-PpoI severely bends its DNA target, resulting in, significant deformations of the minor and major groove near the scissile, phosphate groups. To study the role of conformational changes within the, protein catalyst and the DNA substrate, we have determined the structure, of the enzyme in the absence of bound DNA, performed gel retardation, analyses of DNA binding and bending, and have mutagenized a leucine, residue that contacts an adenine nucleotide at the site of cleavage. The, structure of the L116A/DNA complex has been determined and the effects of, the mutation on affinity and catalysis have been measured. The wild-type, protein displays a rigid-body rotation of its individual subunits upon DNA, binding. Homing site DNA is not detectably bent in the absence of protein, but is sharply bent in both the wild-type and L116A complexes. These, results indicate that binding involves a large distortion of the DNA and a, smaller change in protein conformation. Leucine 116 is critical for, binding and catalysis: it appears to be important for forming a, well-ordered protein-DNA complex at the cleavage site, for maximal, deformation of the DNA, and for desolvation of the nucleotide bases that, are partially unstacked in the enzyme complex.

==About this Structure==
1EVX is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Physarum_polycephalum Physarum polycephalum] with ZN and SO4 as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1EVX OCA]. 

==Reference==
Conformational changes and cleavage by the homing endonuclease I-PpoI: a critical role for a leucine residue in the active site., Galburt EA, Chadsey MS, Jurica MS, Chevalier BS, Erho D, Tang W, Monnat RJ Jr, Stoddard BL, J Mol Biol. 2000 Jul 21;300(4):877-87. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10891275 10891275]
[[Category: Physarum polycephalum]]
[[Category: Single protein]]
[[Category: Chevalier, B.S.]]
[[Category: Erho, D.]]
[[Category: Galburt, E.A.]]
[[Category: Jurica, M.S.]]
[[Category: Stoddard, B.L.]]
[[Category: SO4]]
[[Category: ZN]]
[[Category: dna binding b-sheets; c-terminal exchanged dimer interface]]

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