|2bh9, resolution 2.50Å ()|
X-RAY STRUCTURE OF A DELETION VARIANT OF HUMAN GLUCOSE 6-PHOSPHATE DEHYDROGENASE COMPLEXED WITH STRUCTURAL AND COENZYME NADP
Human glucose-6-phosphate dehydrogenase (G6PD) is NADP(+)-dependent and catalyses the first and rate-limiting step of the pentose phosphate shunt. Binary complexes of the human deletion mutant, DeltaG6PD, with glucose-6-phosphate and NADP(+) have been crystallized and their structures solved to 2.9 and 2.5 A, respectively. The structures are compared with the previously determined structure of the Canton variant of human G6PD (G6PD(Canton)) in which NADP(+) is bound at the structural site. Substrate binding in DeltaG6PD is shown to be very similar to that described previously in Leuconostoc mesenteroides G6PD. NADP(+) binding at the coenzyme site is seen to be comparable to NADP(+) binding in L. mesenteroides G6PD, although some differences arise as a result of sequence changes. The tetramer interface varies slightly among the human G6PD complexes, suggesting flexibility in the predominantly hydrophilic dimer-dimer interactions. In both complexes, Pro172 of the conserved peptide EKPxG is in the cis conformation; it is seen to be crucial for close approach of the substrate and coenzyme during the enzymatic reaction. Structural NADP(+) binds in a very similar way in the DeltaG6PD-NADP(+) complex and in G6PD(Canton), while in the substrate complex the structural NADP(+) has low occupancy and the C-terminal tail at the structural NADP(+) site is disordered. The implications of possible interaction between the structural NADP(+) and G6P are considered.
Structural studies of glucose-6-phosphate and NADP+ binding to human glucose-6-phosphate dehydrogenase., Kotaka M, Gover S, Vandeputte-Rutten L, Au SW, Lam VM, Adams MJ, Acta Crystallogr D Biol Crystallogr. 2005 May;61(Pt 5):495-504. Epub 2005, Apr 20. PMID:15858258
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
[G6PD_HUMAN] Defects in G6PD are the cause of chronic non-spherocytic hemolytic anemia (CNSHA) [MIM:305900]. Deficiency of G6PD is associated with hemolytic anemia in two different situations. First, in areas in which malaria has been endemic, G6PD-deficiency alleles have reached high frequencies (1% to 50%) and deficient individuals, though essentially asymptomatic in the steady state, have a high risk of acute hemolytic attacks. Secondly, sporadic cases of G6PD deficiency occur at a very low frequencies, and they usually present a more severe phenotype. Several types of CNSHA are recognized. Class-I variants are associated with severe NSHA; class-II have an activity <10% of normal; class-III have an activity of 10% to 60% of normal; class-IV have near normal activity.
[G6PD_HUMAN] Produces pentose sugars for nucleic acid synthesis and main producer of NADPH reducing power.
About this Structure
- Kotaka M, Gover S, Vandeputte-Rutten L, Au SW, Lam VM, Adams MJ. Structural studies of glucose-6-phosphate and NADP+ binding to human glucose-6-phosphate dehydrogenase. Acta Crystallogr D Biol Crystallogr. 2005 May;61(Pt 5):495-504. Epub 2005, Apr 20. PMID:15858258 doi:http://dx.doi.org/10.1107/S0907444905002350
- Au SW, Gover S, Lam VM, Adams MJ. Human glucose-6-phosphate dehydrogenase: the crystal structure reveals a structural NADP(+) molecule and provides insights into enzyme deficiency. Structure. 2000 Mar 15;8(3):293-303. PMID:10745013