3csu: Difference between revisions

Revision as of 21:58, 4 May 2008

CATALYTIC TRIMER OF ESCHERICHIA COLI ASPARTATE TRANSCARBAMOYLASE

OverviewOverview

The lack of knowledge of the three-dimensional structure of the trimeric, catalytic (C) subunit of aspartate transcarbamoylase (ATCase) has impeded understanding of the allosteric regulation of this enzyme and left unresolved the mechanism by which the active, unregulated C trimers are inactivated on incorporation into the unliganded (taut or T state) holoenzyme. Surprisingly, the isolated C trimer, based on the 1.9-A crystal structure reported here, resembles more closely the trimers in the T state enzyme than in the holoenzyme:bisubstrate-analog complex, which has been considered as the active, relaxed (R) state enzyme. Unlike the C trimer in either the T state or bisubstrate-analog-bound holoenzyme, the isolated C trimer lacks 3-fold symmetry, and the active sites are partially disordered. The flexibility of the C trimer, contrasted to the highly constrained T state ATCase, suggests that regulation of the holoenzyme involves modulating the potential for conformational changes essential for catalysis. Large differences in structure between the active C trimer and the holoenzyme:bisubstrate-analog complex call into question the view that this complex represents the activated R state of ATCase.

About this StructureAbout this Structure

3CSU is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

ReferenceReference

Assessment of the allosteric mechanism of aspartate transcarbamoylase based on the crystalline structure of the unregulated catalytic subunit., Beernink PT, Endrizzi JA, Alber T, Schachman HK, Proc Natl Acad Sci U S A. 1999 May 11;96(10):5388-93. PMID:10318893 Page seeded by OCA on Sun May 4 21:58:45 2008

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA

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 [[Image:3csu.jpg|left|200px]]
- {{Structure
+<!--
-|PDB= 3csu |SIZE=350|CAPTION= <scene name='initialview01'>3csu</scene>, resolution 1.88&Aring;
+The line below this paragraph, containing "STRUCTURE_3csu", creates the "Structure Box" on the page.
-|SITE=
+You may change the PDB parameter (which sets the PDB file loaded into the applet)
-|LIGAND= <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>
+or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
-|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Aspartate_carbamoyltransferase Aspartate carbamoyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.1.3.2 2.1.3.2] </span>
+or leave the SCENE parameter empty for the default display.
-|GENE= PYRB ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli])
+-->
-|DOMAIN=
+{{STRUCTURE_3csu|  PDB=3csu  |  SCENE=  }}
-|RELATEDENTRY=
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3csu FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3csu OCA], [http://www.ebi.ac.uk/pdbsum/3csu PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=3csu RCSB]</span>
-}}
 '''CATALYTIC TRIMER OF ESCHERICHIA COLI ASPARTATE TRANSCARBAMOYLASE'''
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 [[Category: Endrizzi, J A.]]
 [[Category: Schachman, H K.]]
-[[Category: aspartate)]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May  4 21:58:45 2008''
-[[Category: transferase (carbamoyl-p]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 05:32:49 2008''