1DR8: Structure Of Modified 3-Isopropylmalate Dehydrogenase At The C- Terminus, Hd177

Citation:
Abstract
Thermal stability of the Thermus thermophilus isopropylmalate dehydrogenase enzyme was substantially lost upon the deletion of three residues from the C-terminus. However, the stability was partly recovered by the addition of two, four and seven amino acid residues (called HD177, HD708 and HD711, respectively) to the C-terminal region of the truncated enzyme. Three structures of these mutant enzymes were determined by an X-ray diffraction method. All protein crystals belong to space group P2(1) and their structures were solved by a standard molecular replacement method where the original dimer structure of the A172L mutant was used as a search model. Thermal stability of these mutant enzymes is discussed based on the 3D structure with special attention to the width of the active-site groove and the minor groove, distortion of beta-sheet pillar structure and size of cavity in the domain-domain interface around the C-terminus. Our previous studies revealed that the thermal stability of isopropylmalate dehydrogenase increases when the active-site cleft is closed (the closed form). In the present study it is shown that the active-site cleft can be regulated by open-close movement of the minor groove located at the opposite side to the active-site groove on the same subunit, through a paperclip-like motion.
PDB ID: 1DR8Download
MMDB ID: 12395
PDB Deposition Date: 2000/1/6
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 2.7  Å
Source Organism:
Similar Structures:
Biological Unit for 1DR8: dimeric; determined by author and by software (PISA)
Molecular Components in 1DR8
Label Count Molecule
Proteins (2 molecules)
2
3-isopropylmalate Dehydrogenase(Gene symbol: TTHA1230)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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