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1bxr

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{{STRUCTURE_1bxr| PDB=1bxr | SCENE= }}
{{STRUCTURE_1bxr| PDB=1bxr | SCENE= }}
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'''STRUCTURE OF CARBAMOYL PHOSPHATE SYNTHETASE COMPLEXED WITH THE ATP ANALOG AMPPNP'''
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===STRUCTURE OF CARBAMOYL PHOSPHATE SYNTHETASE COMPLEXED WITH THE ATP ANALOG AMPPNP===
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==Overview==
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Carbamoyl phosphate synthetase (CPS) catalyzes the production of carbamoyl phosphate which is subsequently employed in the metabolic pathways responsible for the synthesis of pyrimidine nucleotides or arginine. The catalytic mechanism of the enzyme occurs through three highly reactive intermediates: carboxyphosphate, ammonia, and carbamate. As isolated from Escherichia coli, CPS is an alpha, beta-heterodimeric protein with its three active sites separated by nearly 100 A. In addition, there are separate binding sites for the allosteric regulators, ornithine, and UMP. Given the sizable distances between the three active sites and the allosteric-binding pockets, it has been postulated that domain movements play key roles for intramolecular communication. Here we describe the structure of CPS from E. coli where, indeed, such a domain movement has occurred in response to nucleotide binding. Specifically, the protein was crystallized in the presence of a nonhydrolyzable analogue, AMPPNP, and its structure determined to 2.1 A resolution by X-ray crystallographic analysis. The B-domain of the carbamoyl phosphate synthetic component of the large subunit closes down over the active-site pocket such that some atoms move by more than 7 A relative to that observed in the original structure. The trigger for this movement resides in the hydrogen-bonding interactions between two backbone amide groups (Gly 721 and Gly 722) and the beta- and gamma-phosphate groups of the nucleotide triphosphate. Gly 721 and Gly 722 are located in a Type III' reverse turn, and this type of secondary structural motif is also observed in D-alanine:D-alanine ligase and glutathione synthetase, both of which belong to the "ATP-grasp" superfamily of proteins. Details concerning the geometries of the two active sites contained within the large subunit of CPS are described.
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(as it appears on PubMed at http://www.pubmed.gov), where 10029528 is the PubMed ID number.
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{{ABSTRACT_PUBMED_10029528}}
==About this Structure==
==About this Structure==
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[[Category: Amidotransferase]]
[[Category: Amidotransferase]]
[[Category: Carbamoyl-phosphate synthase]]
[[Category: Carbamoyl-phosphate synthase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 12:05:29 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 19:53:15 2008''

Revision as of 16:53, 30 June 2008

Image:1bxr.png

Template:STRUCTURE 1bxr

STRUCTURE OF CARBAMOYL PHOSPHATE SYNTHETASE COMPLEXED WITH THE ATP ANALOG AMPPNP

Template:ABSTRACT PUBMED 10029528

About this Structure

1BXR is a Protein complex structure of sequences from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Carbamoyl phosphate synthetase: closure of the B-domain as a result of nucleotide binding., Thoden JB, Wesenberg G, Raushel FM, Holden HM, Biochemistry. 1999 Feb 23;38(8):2347-57. PMID:10029528

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