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| | {{STRUCTURE_2dik| PDB=2dik | SCENE= }} | | {{STRUCTURE_2dik| PDB=2dik | SCENE= }} |
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| - | '''R337A MUTANT OF PYRUVATE PHOSPHATE DIKINASE'''
| + | ===R337A MUTANT OF PYRUVATE PHOSPHATE DIKINASE=== |
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| - | ==Overview==
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| - | Pyruvate phosphate dikinase (PPDK) catalyzes the interconversion of ATP, Pi, and pyruvate with AMP, PPi, and PEP in three partial reactions: (1) E + ATP --> E.ATP --> E-PP.AMP, (2) E-PP.AMP + Pi --> E-PP.AMP.Pi --> E-P.AMP.PPi, and (3) E-P + pyruvate --> E-P.pyruvate --> E.PEP. The Clostridium symbiosum PPDK structure consists of N-terminal, central, and C-terminal domains. The N-terminal and central domains catalyze partial reactions 1 and 2 whereas the C-terminal and central domains catalyze partial reaction 3. The goal of the present work is to determine where on the N-terminal domain catalysis of partial reactions 1 and 2 occurs and, in particular, where the Pi binding site is located. Computer modeling studies implicated Arg337 as a key residue for Pi binding. This role was tested by site-directed mutagenesis. The R337A PPDK was shown to be impaired in catalysis of the forward (kcat 300-fold lower) and reverse (kcat 30-fold lower) full reactions. Time courses for the single turnover reactions were measured to show that catalysis of partial reaction 1 is 5-fold slower in the mutant, catalysis of the second partial reaction is 140-fold slower in the mutant, and catalysis of the third partial reaction is unaffected. With the exception of the mutation site, the crystal structure of the R337A PPDK closely resembles the structure of the wild-type protein. Thus, the altered kinetic properties observed for this mutant are attributed solely to the elimination of the interaction between substrate and the guanidinium group of the Arg337 side chain. On the basis of these findings we propose that the Pi binding site is located within the crevice of the PPDK N-terminal domain, at a site that is flanked by the ATP beta-P and the Mg2+ cofactor.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_9753432}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 9753432 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_9753432}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Kinase]] | | [[Category: Kinase]] |
| | [[Category: Phosphotransferase]] | | [[Category: Phosphotransferase]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 00:29:23 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 04:22:08 2008'' |
Revision as of 01:22, 28 July 2008
Template:STRUCTURE 2dik
R337A MUTANT OF PYRUVATE PHOSPHATE DIKINASE
Template:ABSTRACT PUBMED 9753432
About this Structure
2DIK is a Single protein structure of sequence from Clostridium symbiosum. This structure supersedes the now removed PDB entry 1buk. Full crystallographic information is available from OCA.
Reference
Location of the phosphate binding site within Clostridium symbiosum pyruvate phosphate dikinase., McGuire M, Huang K, Kapadia G, Herzberg O, Dunaway-Mariano D, Biochemistry. 1998 Sep 29;37(39):13463-74. PMID:9753432
Page seeded by OCA on Mon Jul 28 04:22:08 2008
