1pg5

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

spinqualitylabelsall models 1pg5, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1pg5 is a 2 chain structure with sequence from Sulfolobus acidocaldarius. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.6Å Ligands: ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PYRB_SULAC Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed 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. 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 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Aspartate carbamoyltransferase 3D structures

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