1JUK

INDOLE-3-GLYCEROLPHOSPHATE SYNTHASE FROM SULFOLOBUS SOLFATARICUS IN A TRIGONAL CRYSTAL FORM

Summary for 1JUK

• Entry DOI: 10.2210/pdb1juk/pdb
• Descriptor: INDOLE-3-GLYCEROL PHOSPHATE SYNTHASE, SULFATE ION (3 entities in total)
• Functional Keywords: thermophile, tim-barrel, tryptophan biosynthesis, lyase
• Biological source: Sulfolobus solfataricus
• Total number of polymer chains: 1
• Total formula weight: 28722.16

Authors

Knoechel, T.R.,Hennig, M.,Merz, A.,Darimont, B.,Kirschner, K.,Jansonius, J.N. (deposition date: 1996-05-03, release date: 1997-07-07, Last modification date: 2024-05-22)

Primary citation

Knochel, T.R.,Hennig, M.,Merz, A.,Darimont, B.,Kirschner, K.,Jansonius, J.N.
The crystal structure of indole-3-glycerol phosphate synthase from the hyperthermophilic archaeon Sulfolobus solfataricus in three different crystal forms: effects of ionic strength.
J.Mol.Biol., 262:502-515, 1996

PubMed Abstract: Indole-3-glycerol phosphate synthase from the hyperthermophilic archaeon Sulfolobus solfataricus is a monomeric enzyme with the common (beta/alpha)8-fold. Recently, its three-dimensional structure was solved in an orthorhombic crystal form, grown by using 1.3 M ammonium sulfate as precipitating agent. Here we describe the X-ray structure analysis of two new crystal forms of this enzyme that were obtained at medium and low ionic strength, respectively. Hexagonal crystals with space group P3(1)21 and cell dimensions a = 62.4 A, b = 62.4 A, c = 122.9 A, gamma = 120 degrees grew in 0.1 M Mes buffer at pH 6.0 with 30% polyethylene glycol monomethylether as precipitant and 0.2 M ammonium sulfate as co-precipitant. A second crystal form with space group P2(1)2(1)2(1) and cell constants a = 62.6 A, b = 74.0 A, c = 74.2 A was obtained using polyethylene glycol and ethylene glycol as precipitants in 0.1 M Mes buffer at pH 6.5. Both structures were solved by molecular replacement and refined at 2.5 A and 2.0 A resolution, respectively. Although the global folds are almost identical, alternative conformations are observed in flexible loop regions, mostly stabilized by crystal contacts. In none of the three crystal forms is the so-called phosphate binding site empty, suggesting that this position has high affinity for anions with tetrahedrally arranged oxygen atoms. Differences in ionic strength of the crystallization buffer have only minor effects on number and specificity of intramolecular salt bridges. The crystal packing, on the other hand, seems to be influenced by the ionic strength of the solvent, since the number of intermolecular salt bridges in the low ionic strength crystal forms is significantly higher.

PubMed: 8893859
DOI: 10.1006/jmbi.1996.0531

Experimental method

X-RAY DIFFRACTION (2.5 Å)