3csu: Difference between revisions
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New page: left|200px<br /><applet load="3csu" size="450" color="white" frame="true" align="right" spinBox="true" caption="3csu, resolution 1.88Å" /> '''CATALYTIC TRIMER OF ... |
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[[Image:3csu.jpg|left|200px]]<br /><applet load="3csu" size=" | [[Image:3csu.jpg|left|200px]]<br /><applet load="3csu" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="3csu, resolution 1.88Å" /> | caption="3csu, resolution 1.88Å" /> | ||
'''CATALYTIC TRIMER OF ESCHERICHIA COLI ASPARTATE TRANSCARBAMOYLASE'''<br /> | '''CATALYTIC TRIMER OF ESCHERICHIA COLI ASPARTATE TRANSCARBAMOYLASE'''<br /> | ||
==Overview== | ==Overview== | ||
The lack of knowledge of the three-dimensional structure of the trimeric, catalytic (C) subunit of aspartate transcarbamoylase (ATCase) has impeded | 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 Structure== | ==About this Structure== | ||
3CSU is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with CA as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [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] Full crystallographic information is available from [http:// | 3CSU is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [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] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3CSU OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Alber, T.]] | [[Category: Alber, T.]] | ||
[[Category: Beernink, P | [[Category: Beernink, P T.]] | ||
[[Category: Endrizzi, J | [[Category: Endrizzi, J A.]] | ||
[[Category: Schachman, H | [[Category: Schachman, H K.]] | ||
[[Category: CA]] | [[Category: CA]] | ||
[[Category: aspartate)]] | [[Category: aspartate)]] | ||
[[Category: transferase (carbamoyl-p]] | [[Category: transferase (carbamoyl-p]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:08:57 2008'' | ||
