|
Effect of the chlorate and magnesium ions and of the shikimate in the structure of shikimate kinase from Mycobaterium tuberculosis.
Dias, MVB1; Faim, LM1; Bordim, I2, Oliveira, JS2, Santos, BB1, Basso, LA2, Santos, DS2; Azevedo Jr., WF1,2
1 IBILCE - UNESP - São José do Rio Preto - SP
2 PUC - Porto Alegre - RS
The shikimate pathway
converts phosphoenolpyruvate and erytrose 4-phosphate in chorismate.
The enzymes in this pathway are targets for the development of
antimicrobial agents because it is essential for bacteria and it is
absent in mammals. The shikimate kinase is the fifth enzyme of this
pathway and realizes the phosphorylation of the 3-hydroxyl group of
shikimate using ATP as a co-substrate. Cl- plays an important role in the affinity of SK for ATP, while the Mg2+ can be involved in the nucleophilic attack on the
ATP molecule, and the shikimate seems to cause conformational changes
in the SK structure. In this work, we show the structural alterations
cased for Cl-, Mg2+ and shikimate in the structure of SK from Mycobacterium tuberculosis (MtSK). The MtSK was crystallized using the diffusion vapor method in two complexes different (MtSK:ADP:Mg2+, MtSK:ADP:shikimate). The refinement was performed using the program REFMAC5 and visual inspection was realized for XtalView. The
MtSK:ADP:shikimate was crystallized in the space group p3221,
presenting one molecule in the asymmetric unit and was solved to 1.93Å.
MtSK:ADP:Mg2+ was crystallized in the space group p212121
presenting four molecules in the asymmetric unit and was solved to
2.8Å. One of molecules of asymmetric unit of complex MtSK:ADP:shikimate
did not present the Cl-. The MtSK:ADP:shikimate was compared with the MtSK:ADP:Mg2+:shikimate
deposited in the PDB. We observed that occurs differences in the
position of molecule of shikimate, mainly in the 3-hidroxil group,
which provably is due to Mg2+. The Mg2+ seem to be related with ordinance of 3-hidroxil group of the shikimate. The Cl- seems
to be related the ordinance of molecule of ATP/ADP toward more next of
the shikimate, or still can be occupying the position of third phosphate
of ATP molecule. The shikimate really case a large influence in the
structure of MtSK. In the absence of shikimate, the MtSK present a
conformation more opened. The informations present here can be useful
to understand the mechanism of catalysis of SK and also for design of
drugs based in structure against disease caused for microorganisms.
Fapesp 03/12472-2
|