HDim1/U5-15kD: Difference between revisions
New page: == Structure of the hDim1/U5-15kD Protein == by Kelly Hrywkiw {{STRUCTURE_1qgv | PDB=1qgv | SCENE= }} __TOC__ =Introduction= The protein Dim1 goes by many names, hDim1/U5-15kD in... |
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<StructureSection load='1qgv' size='450' side='right' scene='Sandbox_502/Hdim1_start_scene/2' caption='Human spliceosomal protein U5-15kD (PDB code [[1qgv]]) '> | |||
== Structure of the hDim1/U5-15kD Protein == | == Structure of the hDim1/U5-15kD Protein == | ||
by Kelly Hrywkiw | by Kelly Hrywkiw | ||
__TOC__ | __TOC__ | ||
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==Oxidized Full Length Form (hDim1)== | ==Oxidized Full Length Form (hDim1)== | ||
The thioredoxin-like fold of <scene name='Sandbox_502/Hdim1_start_scene/2'>hDim1</scene> follows the arrangement of a five stranded β-sheet, consisting of parallel and antiparallel stands, surrounded by three α-helices, where the loop between β4 and α3 could not be resolved. When compared to human thioredoxin there are a total of 37 additional residues in hDim1, which result in several structural differences. For example, the N-terminus is extended by three residues, in the α2-β2 loop one residue is inserted, after β4 nine are inserted, before the α2 helix two are inserted, and <scene name='Sandbox_502/Hdim1_c-terminal_extension/1'>22 extend the C-terminus</scene>. This results in an altered structure where β4 and β5 appear to be pulled away from the β-sheet leaving a <scene name='Sandbox_502/Hdim1cleft/1'>cleft</scene> between β3 and β4<ref name ="Reuter"/>. | The thioredoxin-like fold of <scene name='Sandbox_502/Hdim1_start_scene/2'>hDim1</scene> follows the arrangement of a five stranded β-sheet, consisting of parallel and antiparallel stands, surrounded by three α-helices, where the loop between β4 and α3 could not be resolved. When compared to human thioredoxin there are a total of 37 additional residues in hDim1, which result in several structural differences. For example, the N-terminus is extended by three residues, in the α2-β2 loop one residue is inserted, after β4 nine are inserted, before the α2 helix two are inserted, and <scene name='Sandbox_502/Hdim1_c-terminal_extension/1'>22 extend the C-terminus</scene>. This results in an altered structure where β4 and β5 appear to be pulled away from the β-sheet leaving a <scene name='Sandbox_502/Hdim1cleft/1'>cleft</scene> between β3 and β4<ref name ="Reuter"/>. | ||
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==Reduced Dominant Negative Form (hDim1-128)== | ==Reduced Dominant Negative Form (hDim1-128)== | ||
The removal of the C-terminal extension induces cell cycle arrest in [http://en.wikipedia.org/wiki/G2_phase G2], however does not affect localization, steady-state levels, or phosphorylation of the protein<ref name ="Zhang 2003"/>. This suggests that it may be the interactions to other proteins and substrates that are disrupted by the removal of the C-terminal extension <ref name ="zhang 1999"/>. It is therefore important to understand the functional changes that the presence of the C-terminal extension creates . | |||
The removal of the C-terminal extension induces cell cycle arrest in [http://en.wikipedia.org/wiki/G2_phase G2], however does not affect localization, steady-state levels, or phosphorylation of the protein<ref name ="Zhang 2003"/>. This suggests that it may be the interactions to other proteins and substrates that are disrupted by the removal of the C-terminal extension <ref name ="zhang 1999"/>. It is therefore important to understand the | |||
The structure of <scene name='Sandbox_502/Hdim1-128_start_scene/2'>hDim1-128</scene> compared to hDim1 is remarkably similar, where the same mixed β-sheet flanked by three α-helices is seen. However a prominent difference includes the loss of the β-strand comprised of residues 129-131 and 91-93. By comparing the circular dichroism spectra of hDim1 to hDim1-128 there is a decrease in α helical structure upon truncation. This suggests that the C-terminal region consists of a partially α-helical region in solution, which contradicts the findings of the hDim1 crystal structure. However, it possible that this region is naturally flexible allowing it to adopt several conformations, thereby enabling it to interact with various regions of the spliceosome as it changes through a splicing event. Interestingly, when the basic residues <scene name='Sandbox_502/Hdim1-128_arg86_and_lys88/1'>Arg86 and Lys88</scene>, which were suggested to partake in the formation of a positively charged region in hDim1 (see above), were mutated, there was a major decrease in structural stability and cooperative folding<ref name ="Zhang 2003"/>. | |||
</StructureSection> | |||
=Additional Resources= | =Additional Resources= | ||
*[http://www.rcsb.org/pdb/explore/explore.do?structureId=1QGV HUMAN SPLICEOSOMAL PROTEIN U5-15KD, in the RCSB Protein Data Bank] | *[http://www.rcsb.org/pdb/explore/explore.do?structureId=1QGV HUMAN SPLICEOSOMAL PROTEIN U5-15KD, in the RCSB Protein Data Bank] | ||