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| | {{STRUCTURE_1xk6| PDB=1xk6 | SCENE= }} | | {{STRUCTURE_1xk6| PDB=1xk6 | SCENE= }} |
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| - | '''Crystal Structure- P1 form- of Escherichia coli Crotonobetainyl-CoA: carnitine CoA Transferase (CaiB)'''
| + | ===Crystal Structure- P1 form- of Escherichia coli Crotonobetainyl-CoA: carnitine CoA Transferase (CaiB)=== |
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| - | ==Overview==
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| - | L-Carnitine (R-[-]-3-hydroxy-4-trimethylaminobutyrate) is found in both eukaryotic and prokaryotic cells and participates in diverse processes including long-chain fatty-acid transport and osmoprotection. The enzyme crotonobetainyl/gamma-butyrobetainyl-CoA:carnitine CoA-transferase (CaiB; E.C. 2.8.3.-) catalyzes the first step in carnitine metabolism, leading to the final product gamma-butyrobetaine. The crystal structures of Escherichia coli apo-CaiB, as well as its Asp169Ala mutant bound to CoA and to carnitinyl-CoA, have been determined and refined to 1.6, 2.4, and 2.4 A resolution, respectively. CaiB is composed of two identical circular chains that together form an intertwined dimer. Each monomer consists of a large domain, containing a Rossmann fold, and a small domain. The monomer and dimer resemble those of formyl-CoA transferase from Oxalobacter formigenes, as well as E. coli YfdW, a putative type-III CoA transferase of unknown function. The CoA cofactor-binding site is formed at the interface of the large domain of one monomer and the small domain from the second monomer. Most of the protein-CoA interactions are formed with the Rossmann fold domain. While the location of cofactor binding is similar in the three proteins, the specific CoA-protein interactions vary somewhat between CaiB, formyl-CoA transferase, and YfdW. CoA binding results in a change in the relative positions of the large and small domains compared with apo-CaiB. The observed carnitinyl-CoA product in crystals of the CaiB Asp169Ala mutant cocrystallized with crotonoyl-CoA and carnitine could result from (i) a catalytic mechanism involving a ternary enzyme-substrate complex, independent of a covalent anhydride intermediate with Asp169, (ii) a spontaneous reaction of the substrates in solution, followed by binding to the enzyme, or (iii) an involvement of another residue substituting functionally for Asp169, such as Glu23.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_15823031}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 15823031 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_15823031}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Coa transferase]] | | [[Category: Coa transferase]] |
| | [[Category: Crotonobetainyl coa]] | | [[Category: Crotonobetainyl coa]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 15:08:06 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 02:26:55 2008'' |
Revision as of 23:26, 28 July 2008
Template:STRUCTURE 1xk6
Crystal Structure- P1 form- of Escherichia coli Crotonobetainyl-CoA: carnitine CoA Transferase (CaiB)
Template:ABSTRACT PUBMED 15823031
About this Structure
1XK6 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Crystal structure of Escherichia coli crotonobetainyl-CoA: carnitine CoA-transferase (CaiB) and its complexes with CoA and carnitinyl-CoA., Rangarajan ES, Li Y, Iannuzzi P, Cygler M, Matte A, Biochemistry. 2005 Apr 19;44(15):5728-38. PMID:15823031
Page seeded by OCA on Tue Jul 29 02:26:55 2008
