کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2052885 | 1074244 | 2006 | 8 صفحه PDF | دانلود رایگان |

The crystal structure of β-hydroxyacyl acyl carrier protein dehydratase of Plasmodium falciparum (PfFabZ) has been determined at a resolution of 2.4 Å. PfFabZ has been found to exist as a homodimer (d-PfFabZ) in the crystals of the present study in contrast to the reported hexameric form (h-PfFabZ) which is a trimer of dimers crystallized in a different condition. The catalytic sites of this enzyme are located in deep narrow tunnel-shaped pockets formed at the dimer interface. A histidine residue from one subunit of the dimer and a glutamate residue from the other subunit lining the tunnel form the catalytic dyad in the reported crystal structures. While the position of glutamate remains unaltered in the crystal structure of d-PfFabZ compared to that in h-PfFabZ, the histidine residue takes up an entirely different conformation and moves away from the tunnel leading to a His-Phe cis–trans peptide flip at the histidine residue. In addition, a loop in the vicinity has been observed to undergo a similar flip at a Tyr–Pro peptide bond. These alterations not only prevent the formation of a hexamer but also distort the active site geometry resulting in a dimeric form of FabZ that is incapable of substrate binding. The dimeric state and an altered catalytic site architecture make d-PfFabZ distinctly different from the FabZ structures described so far. Dynamic light scattering and size exclusion chromatographic studies clearly indicate a pH-related switching of the dimers to active hexamers.
Journal: FEBS Letters - Volume 580, Issue 11, 15 May 2006, Pages 2653–2660