Liebold, Christoph and List, Felix and Kalbitzer, Hans Robert and Sterner, Reinhard and Brunner, Eike (2010) The interaction of ammonia and xenon with the imidazole glycerol phosphate synthase from Thermotoga maritima as detected by NMR spectroscopy. PROTEIN SCIENCE, 19 (9). pp. 1774-1782. ISSN 0961-8368, 1469-896X
Full text not available from this repository. (Request a copy)Abstract
The imidazole glycerol phosphate (ImGP) synthase from the hyperthermophilic bacterium Thermotoga maritima is a 1:1 complex of the glutaminase subunit HisH and the cyclase subunit HisF. It has been proposed that ammonia generated by HisH is transported through a channel to the active site of HisF, which generates intermediates of histidine (ImGP) and de novo biosynthesis of 5-aminoimidazole-4-carboxamideribotide. Solution NMR spectroscopy of ammonium chloride-titrated samples was used to study the interaction of NH3 with amino acids inside this channel. Although numerous residues showed N-15 chemical shift changes, most of these changes were caused by nonspecific ionic strength effects. However, several interactions appeared to be specific. Remarkably, the amino acid residue Thr 78-which is located in the central channel shows a large chemical shift change upon titration with ammonium chloride. This result and the reduced catalytic activity of the Thr78Met mutant indicate a special role of this residue in ammonia channeling. To detect and further characterize internal cavities in HisF, which might for example contribute to ammonia channeling, the interaction of HisF with the noble gas xenon was analyzed by solution NMR spectroscopy using H-1-N-15 HSQC experiments. The results indicate that HisF contains three distinct internal cavities, which could be identified by xenon-induced chemical shift changes of the neighboring amino acid residues. Two of these cavities are located at the active site at opposite ends of the substrate N'-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamide-ribonucleotide (PRFAR) binding groove. The third cavity is located in the interior of the central beta-barrel of HisF and overlaps with the putative ammonia transport channel.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CHEMICAL-SHIFT; STAPHYLOCOCCUS-CARNOSUS; (BETA/ALPHA)(8) BARREL; HISTIDINE BIOSYNTHESIS; PROTEIN INTERACTIONS; STRUCTURAL EVIDENCE; BIENZYME COMPLEX; ASSIGNMENT; EVOLUTION; CAVITIES; ImGP-synthase; HisF; Thermotoga maritime; NMR spectroscopy; substrate channeling; NH3; xenon |
| Subjects: | 500 Science > 570 Life sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Biophysik und physikalische Biochemie > Prof. Dr. Dr. Hans Robert Kalbitzer Biology, Preclinical Medicine > Institut für Biophysik und physikalische Biochemie > Prof. Dr. Reinhard Sterner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 15 Jul 2020 08:36 |
| Last Modified: | 15 Jul 2020 08:36 |
| URI: | https://pred.uni-regensburg.de/id/eprint/24293 |
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