1sja

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{{STRUCTURE_1sja| PDB=1sja | SCENE= }}
{{STRUCTURE_1sja| PDB=1sja | SCENE= }}
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'''X-ray structure of o-Succinylbenzoate Synthase complexed with N-acetylmethionine'''
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===X-ray structure of o-Succinylbenzoate Synthase complexed with N-acetylmethionine===
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==Overview==
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Divergent evolution of enzyme function is commonly explained by a gene duplication event followed by mutational changes that allow the protein encoded by the copy to acquire a new function. An alternate hypothesis is that this process is facilitated when the progenitor enzyme acquires a second function while maintaining the original activity. This phenomenon has been suggested to occur in the o-succinylbenzoate synthase (OSBS) from a species of Amycolatopsis that catalyzes not only the physiological syn-dehydration reaction of 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate but also an accidental racemization of N-acylamino acids [Palmer, D. R., Garrett, J. B., Sharma, V., Meganathan, R., Babbitt, P. C., and Gerlt, J. A. (1999) Biochemistry 38, 4252-4258]. To understand the molecular basis of this promiscuity, three-dimensional structures of liganded complexes of this enzyme have been determined, including the product of the OSBS reaction and three N-acylamino acid substrates for the N-acylamino acid racemase (NAAAR) reaction, N-acetylmethionine, N-succinylmethionine, and N-succinylphenylglycine, to 2.2, 2.3, 2.1, and 1.9 A resolution, respectively. These structures show how the active-site cavity can accommodate both the hydrophobic substrate for the OSBS reaction and the substrates for the accidental NAAAR reaction. As expected, the N-acylamino acid is sandwiched between lysines 163 and 263, which function as the catalytic bases for the abstraction of the alpha-proton in the (R)- and (S)-racemization reactions, respectively [Taylor Ringia, E. A., Garrett, J. B, Thoden, J. B., Holden, H. M., Rayment, I., and Gerlt, J. A. (2004) Biochemistry 42, 224-229]. Importantly, the protein forms specific favorable interactions with the hydrophobic amino acid side chain, alpha-carbon, carboxylate, and the polar components of the N-acyl linkage. Accommodation of the components of the N-acyl linkage appears to be the reason that this enzyme is capable of a racemization reaction on these substrates, whereas the orthologous OSBS from Escherichia coli lacks this functionality.
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{{ABSTRACT_PUBMED_15134446}}
==About this Structure==
==About this Structure==
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[[Category: Thoden, J B.]]
[[Category: Thoden, J B.]]
[[Category: Racemase]]
[[Category: Racemase]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 13:03:03 2008''

Revision as of 10:03, 29 July 2008

Image:1sja.png

Template:STRUCTURE 1sja

X-ray structure of o-Succinylbenzoate Synthase complexed with N-acetylmethionine

Template:ABSTRACT PUBMED 15134446

About this Structure

1SJA is a Single protein structure of sequence from Amycolatopsis sp.. Full crystallographic information is available from OCA.

Reference

Evolution of enzymatic activity in the enolase superfamily: structural studies of the promiscuous o-succinylbenzoate synthase from Amycolatopsis., Thoden JB, Taylor Ringia EA, Garrett JB, Gerlt JA, Holden HM, Rayment I, Biochemistry. 2004 May 18;43(19):5716-27. PMID:15134446

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