2DP3

Crystal structure of a double mutant (C202A/A198V) of Triosephosphate isomerase from giardia lamblia

Summary for 2DP3

• Entry DOI: 10.2210/pdb2dp3/pdb
• Descriptor: Triosephosphate isomerase, SULFATE ION (3 entities in total)
• Functional Keywords: triosephosphate isomerase, giardia, enzyme, alpha/beta barrel, isomerase
• Biological source: Giardia intestinalis
• Total number of polymer chains: 1
• Total formula weight: 28320.43

Authors

Diaz, A.,Reyes-Vivas, H.,Lopez-Velazquez, G. (deposition date: 2006-05-05, release date: 2007-01-02, Last modification date: 2023-10-25)

Primary citation

Reyes-Vivas, H.,Diaz, A.,Peon, J.,Mendoza-Hernandez, G.,Hernandez-Alcantara, G.,De la Mora-De la Mora, I.,Enriquez-Flores, S.,Dominguez-Ramirez, L.,Lopez-Velazquez, G.
Disulfide Bridges in the Mesophilic Triosephosphate Isomerase from Giardia lamblia Are Related to Oligomerization and Activity
J.Mol.Biol., 365:752-763, 2007

PubMed Abstract: Triosephosphate isomerase from the mesophile Giardia lamblia (GlTIM) is the only known TIM with natural disulfide bridges. We previously found that oxidized and reduced thiol states of GlTIM are involved in the interconversion between native dimers and higher oligomeric species, and in the regulation of enzymatic activity. Here, we found that trophozoites and cysts have different oligomeric species of GlTIM and complexes of GlTIM with other proteins. Our data indicate that the internal milieu of G. lamblia is favorable for the formation of disulfide bonds. Enzyme mutants of the three most solvent exposed Cys of GlTIM (C202A, C222A, and C228A) were prepared to ascertain their contribution to oligomerization and activity. The data show that the establishment of a disulfide bridge between two C202 of two dimeric GlTIMs accounts for multimerization. In addition, we found that the establishment of an intramonomeric disulfide bond between C222 and C228 abolishes catalysis. Multimerization and inactivation are both reversed by reducing conditions. The 3D structure of the C202A GlTIM was solved at 2.1 A resolution, showing that the environment of the C202 is prone to hydrophobic interactions. Molecular dynamics of an in silico model of GlTIM when the intramonomeric disulfide bond is formed, showed that S216 is displaced 4.6 A from its original position, causing loss of hydrogen bonds with residues of the active-site loop. This suggests that this change perturb the conformational state that aligns the catalytic center with the substrate, inducing enzyme inactivation.

PubMed: 17095008
DOI: 10.1016/j.jmb.2006.10.053

Experimental method

X-RAY DIFFRACTION (2.1 Å)