Schneider, Birgit, Knöchel, Thorsten, Darimont, Beatrice, Hennig, Michael, Dietrich, Susanne, Babinger, Karin, Kirschner, Kasper and Sterner, Reinhard
(2005)
Role of the N-terminal extension of the (betaalpha)8-barrel enzyme indole-3-glycerol phosphate synthase for its fold, stability, and catalytic activity.
Biochemistry 44 (50), pp. 16405-12.
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Abstract
Indole-3-glycerol phosphate synthase (IGPS) catalyzes the fifth step in the biosynthesis of tryptophan. It belongs to the large and versatile family of (betaalpha)(8)-barrel enzymes but has an unusual N-terminal extension of about 40 residues. Limited proteolysis with trypsin of IGPS from both Sulfolobus solfataricus (sIGPS) and Thermotoga maritima (tIGPS) removes about 25 N-terminal residues and ...
Abstract
Indole-3-glycerol phosphate synthase (IGPS) catalyzes the fifth step in the biosynthesis of tryptophan. It belongs to the large and versatile family of (betaalpha)(8)-barrel enzymes but has an unusual N-terminal extension of about 40 residues. Limited proteolysis with trypsin of IGPS from both Sulfolobus solfataricus (sIGPS) and Thermotoga maritima (tIGPS) removes about 25 N-terminal residues and one of the two extra helices contained therein. To assess the role of the extension, the N-terminally truncated variants sIGPSDelta(1-26) and tIGPSDelta(1-25) were produced recombinantly in Escherichia coli, purified, and characterized in comparison to the wild-type enzymes. Both sIGPSDelta(1-26) and tIGPSDelta(1-25) have unchanged oligomerization states and turnover numbers. In contrast, their Michaelis constants for the substrate 1-(o-carboxyphenylamino)-1-deoxyribulose 5-phosphate are increased, and their resistance toward unfolding induced by heat and guanidinium chloride is decreased. sIGPSDelta(1-26) was crystallized, and its X-ray structure was solved at 2.8 A resolution. The comparison with the known structure of sIGPS reveals small differences that account for its reduced substrate affinity and protein stability. The structure of the core of sIGPSDelta(1-26) is, however, unchanged compared to sIGPS, explaining its retained catalytic activity and consistent with the idea that it evolved from the same ancestor as the phosphoribosyl anthranilate isomerase and the alpha-subunit of tryptophan synthase. These (betaalpha)(8)-barrel enzymes catalyze the reactions preceding and following IGPS in tryptophan biosynthesis but lack an N-terminal extension.
Export bibliographical data
| Item type: | Article |
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| Date: | 2005 |
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| Institutions: | Biology, Preclinical Medicine > Institut für Biophysik und physikalische Biochemie > Prof. Dr. Reinhard Sterner |
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| Identification Number: | | Value | Type |
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| 16342933 | PubMed ID | | 10.1021/bi051640n | DOI |
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| Classification: | | Notation | Type |
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| Amino Acid Sequence | MESH | | Base Sequence | MESH | | Biopolymers | MESH | | Catalysis | MESH | | DNA Primers | MESH | | Enzyme Stability | MESH | | Hydrolysis | MESH | | Indole-3-Glycerol-Phosphate Synthase/metabolism | MESH | | Models, Molecular | MESH | | Molecular Sequence Data | MESH | | Protein Folding | MESH | | Sequence Homology, Amino Acid | MESH | | Sulfolobus solfataricus/enzymology | MESH | | Thermotoga maritima/enzymology | MESH |
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| Dewey Decimal Classification: | 500 Science > 570 Life sciences |
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| Status: | Published |
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| Refereed: | Yes, this version has been refereed |
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| Created at the University of Regensburg: | Yes |
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| Item ID: | 13676 |
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