Structural analyses of Trichomonas vaginalis pyrophosphate-dependent phosphofructokinase (TvPPi-PFK)
Avery Chiu, Lijun Liu, Steve Seibold
1Dartmouth Cancer Center, One Medical Center Drive, Lebanon, NH, 03756, USA.
Abstract:
Trichomonas vaginalis causes trichomoniasis, the most common non-viral sexually transmitted disease in humans. T. vaginalis pyrophosphate-dependent phosphofructokinase ( Tv PPi-PFK) is a putative target for rational, structure-based drug discovery, given its absence in mammals and its importance for parasite survival. Tv PPi-PFK is a cytosolic enzyme that catalyzes the phosphorylation of fructose-6-phosphate using pyrophosphate (PPi) as the phosphoryl donor. This reversible reaction, catalyzed by Tv PPi-PFK, is the first committed step in glycolysis. Its reverse reaction is vital for gluconeogenesis in T. vaginalis . The purification, crystallization, structure determination, and crystal structures of Tv PPi-PFK are reported. Tv PPi-PFK is the first reported eukaryotic PPi-PFK structure. Tv PPi-PFK retains the overall PPi-PFK topology observed in bacterial PPi-PFK including conserved motifs essential for pyrophosphate binding and PPi-PFK catalytic activity. In addition to the catalytic PPi-PFK binding sites, Tv PPi-PFK has two additional ligand binding sites. The first binds AMP usurped during protein production and helps stabilize the Tv PPi-PFK tetramer. A second ligand binding site was observed in proximity to the AMP-binding site and accommodates sugar phosphates soaked into preformed crystals. This sugar phosphates binding site is distinct from the Tv PPi-PFK active site that binds fructose-6-phosphate. Future mutagenesis and activity studies are planned to determine the relevance of both sites.
Synopsis:
The production, crystallization, and crystal structures of a pyrophosphate-dependent phosphofructokinase from Trichomonas vaginalis ( Tv PPi-PFK) are reported. Tv PPi-PFK has a prototypical PPi-PFK active site as well as unexpected AMP and sugar-phosphate binding sites at the dimer interface.
Related Concept Videos
Trichomoniasis
Phosphoinositides and PIPs
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Protein Kinases and Phosphatases
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...
Protein Kinases and Phosphatases
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...
ATP Synthase: Structure
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...


