1pg5: Difference between revisions

Revision as of 15:28, 21 February 2008

CRYSTAL STRUCTURE OF THE UNLIGATED (T-STATE) ASPARTATE TRANSCARBAMOYLASE FROM THE EXTREMELY THERMOPHILIC ARCHAEON SULFOLOBUS ACIDOCALDARIUS

OverviewOverview

Aspartate carbamoyltransferase (ATCase) is a model enzyme for understanding allosteric effects. The dodecameric complex exists in two main states (T and R) that differ substantially in their quaternary structure and their affinity for various ligands. Many hypotheses have resulted from the structure of the Escherichia coli ATCase, but so far other crystal structures to test these have been lacking. Here, we present the tertiary and quaternary structure of the T state ATCase of the hyperthermophilic archaeon Sulfolobus acidocaldarius (SaATC(T)), determined by X-ray crystallography to 2.6A resolution. The quaternary structure differs from the E.coli ATCase, by having altered interfaces between the catalytic (C) and regulatory (R) subunits, and the presence of a novel C1-R2 type interface. Conformational differences in the 240 s loop region of the C chain and the C-terminal region of the R chain affect intersubunit and interdomain interfaces implicated previously in the allosteric behavior of E.coli ATCase. The allosteric-zinc binding domain interface is strengthened at the expense of a weakened R1-C4 type interface. The increased hydrophobicity of the C1-R1 type interface may stabilize the quaternary structure. Catalytic trimers of the S.acidocaldarius ATCase are unstable due to a drastic weakening of the C1-C2 interface. The hyperthermophilic ATCase presents an interesting example of how an allosteric enzyme can adapt to higher temperatures. The structural rearrangement of this thermophilic ATCase may well promote its thermal stability at the expense of changes in the allosteric behavior.

About this StructureAbout this Structure

1PG5 is a Protein complex structure of sequences from Sulfolobus acidocaldarius with as ligand. Active as Aspartate carbamoyltransferase, with EC number 2.1.3.2 Full crystallographic information is available from OCA.

ReferenceReference

Crystal structure of T state aspartate carbamoyltransferase of the hyperthermophilic archaeon Sulfolobus acidocaldarius., De Vos D, Van Petegem F, Remaut H, Legrain C, Glansdorff N, Van Beeumen JJ, J Mol Biol. 2004 Jun 11;339(4):887-900. PMID:15165857

Page seeded by OCA on Thu Feb 21 14:28:27 2008

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OCA

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-[[Image:1pg5.gif|left|200px]]<br /><applet load="1pg5" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1pg5.gif|left|200px]]<br /><applet load="1pg5" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1pg5, resolution 2.60&Aring;" />
 '''CRYSTAL STRUCTURE OF THE UNLIGATED (T-STATE) ASPARTATE TRANSCARBAMOYLASE FROM THE EXTREMELY THERMOPHILIC ARCHAEON SULFOLOBUS ACIDOCALDARIUS'''<br />
 ==Overview==
-Aspartate carbamoyltransferase (ATCase) is a model enzyme for, understanding allosteric effects. The dodecameric complex exists in two, main states (T and R) that differ substantially in their quaternary, structure and their affinity for various ligands. Many hypotheses have, resulted from the structure of the Escherichia coli ATCase, but so far, other crystal structures to test these have been lacking. Here, we present, the tertiary and quaternary structure of the T state ATCase of the, hyperthermophilic archaeon Sulfolobus acidocaldarius (SaATC(T)), determined by X-ray crystallography to 2.6A resolution. The quaternary, structure differs from the E.coli ATCase, by having altered interfaces, between the catalytic (C) and regulatory (R) subunits, and the presence of, a novel C1-R2 type interface. Conformational differences in the 240 s loop, region of the C chain and the C-terminal region of the R chain affect, intersubunit and interdomain interfaces implicated previously in the, allosteric behavior of E.coli ATCase. The allosteric-zinc binding domain, interface is strengthened at the expense of a weakened R1-C4 type, interface. The increased hydrophobicity of the C1-R1 type interface may, stabilize the quaternary structure. Catalytic trimers of the, S.acidocaldarius ATCase are unstable due to a drastic weakening of the, C1-C2 interface. The hyperthermophilic ATCase presents an interesting, example of how an allosteric enzyme can adapt to higher temperatures. The, structural rearrangement of this thermophilic ATCase may well promote its, thermal stability at the expense of changes in the allosteric behavior.
+Aspartate carbamoyltransferase (ATCase) is a model enzyme for understanding allosteric effects. The dodecameric complex exists in two main states (T and R) that differ substantially in their quaternary structure and their affinity for various ligands. Many hypotheses have resulted from the structure of the Escherichia coli ATCase, but so far other crystal structures to test these have been lacking. Here, we present the tertiary and quaternary structure of the T state ATCase of the hyperthermophilic archaeon Sulfolobus acidocaldarius (SaATC(T)), determined by X-ray crystallography to 2.6A resolution. The quaternary structure differs from the E.coli ATCase, by having altered interfaces between the catalytic (C) and regulatory (R) subunits, and the presence of a novel C1-R2 type interface. Conformational differences in the 240 s loop region of the C chain and the C-terminal region of the R chain affect intersubunit and interdomain interfaces implicated previously in the allosteric behavior of E.coli ATCase. The allosteric-zinc binding domain interface is strengthened at the expense of a weakened R1-C4 type interface. The increased hydrophobicity of the C1-R1 type interface may stabilize the quaternary structure. Catalytic trimers of the S.acidocaldarius ATCase are unstable due to a drastic weakening of the C1-C2 interface. The hyperthermophilic ATCase presents an interesting example of how an allosteric enzyme can adapt to higher temperatures. The structural rearrangement of this thermophilic ATCase may well promote its thermal stability at the expense of changes in the allosteric behavior.
 ==About this Structure==
-PG5 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Sulfolobus_acidocaldarius Sulfolobus acidocaldarius] with ZN 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://ispc.weizmann.ac.il/oca-bin/ocashort?id=1PG5 OCA].
+PG5 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Sulfolobus_acidocaldarius Sulfolobus acidocaldarius] with <scene name='pdbligand=ZN:'>ZN</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=1PG5 OCA].
 ==Reference==
@@ Line 14: / Line 14: @@
 [[Category: Protein complex]]
 [[Category: Sulfolobus acidocaldarius]]
-[[Category: Beeumen, J.J.Van.]]
+[[Category: Beeumen, J J.Van.]]
 [[Category: Glansdorff, N.]]
 [[Category: Legrain, C.]]
-[[Category: Petegem, F.Van.]]
+[[Category: Petegem, F Van.]]
 [[Category: Remaut, H.]]
-[[Category: Vos, D.De.]]
+[[Category: Vos, D De.]]
 [[Category: ZN]]
 [[Category: transferase]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 23:46:48 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:28:27 2008''