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1os1

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{{STRUCTURE_1os1| PDB=1os1 | SCENE= }}
{{STRUCTURE_1os1| PDB=1os1 | SCENE= }}
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'''Structure of Phosphoenolpyruvate Carboxykinase complexed with ATP,Mg, Ca and pyruvate.'''
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===Structure of Phosphoenolpyruvate Carboxykinase complexed with ATP,Mg, Ca and pyruvate.===
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==Overview==
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The 1.8-A resolution structure of the ATP-Mg(2+)-Ca(2+)-pyruvate quinary complex of Escherichia coli phosphoenolpyruvate carboxykinase (PCK) is isomorphous to the published complex ATP-Mg(2+)-Mn(2+)-pyruvate-PCK, except for the Ca(2+) and Mn(2+) binding sites. Ca(2+) was formerly implicated as a possible allosteric regulator of PCK, binding at the active site and at a surface activating site (Glu508 and Glu511). This report found that Ca(2+) bound only at the active site, indicating that there is likely no surface allosteric site. (45)Ca(2+) bound to PCK with a K(d) of 85 micro M and n of 0.92. Glu508Gln Glu511Gln mutant PCK had normal activation by Ca(2+). Separate roles of Mg(2+), which binds the nucleotide, and Ca(2+), which bridges the nucleotide and the anionic substrate, are implied, and the catalytic mechanism of PCK is better explained by studies of the Ca(2+)-bound structure. Partial trypsin digestion abolishes Ca(2+) activation (desensitizes PCK). N-terminal sequencing identified sensitive sites, i.e., Arg2 and Arg396. Arg2Ser, Arg396Ser, and Arg2Ser Arg396Ser (double mutant) PCKs altered the kinetics of desensitization. C-terminal residues 397 to 540 were removed by trypsin when wild-type PCK was completely desensitized. Phe409 and Phe413 interact with residues in the Ca(2+) binding site, probably stabilizing the C terminus. Phe409Ala, DeltaPhe409, Phe413Ala, Delta397-521 (deletion of residues 397 to 521), Arg396(TAA) (stop codon), and Asp269Glu (Ca(2+) site) mutations failed to desensitize PCK and, with the exception of Phe409Ala, appeared to have defects in the synthesis or assembly of PCK, suggesting that the structure of the C-terminal domain is important in these processes.
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{{ABSTRACT_PUBMED_12837799}}
==About this Structure==
==About this Structure==
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[[Category: Enzyme mechanism]]
[[Category: Enzyme mechanism]]
[[Category: Phosphotransfer,calcium,activation]]
[[Category: Phosphotransfer,calcium,activation]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 04:12:52 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 22:21:51 2008''

Revision as of 19:21, 27 July 2008

Image:1os1.png

Template:STRUCTURE 1os1

Structure of Phosphoenolpyruvate Carboxykinase complexed with ATP,Mg, Ca and pyruvate.

Template:ABSTRACT PUBMED 12837799

About this Structure

1OS1 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Mechanisms of activation of phosphoenolpyruvate carboxykinase from Escherichia coli by Ca2+ and of desensitization by trypsin., Sudom A, Walters R, Pastushok L, Goldie D, Prasad L, Delbaere LT, Goldie H, J Bacteriol. 2003 Jul;185(14):4233-42. PMID:12837799

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