The Crystal Structure of Phosphoglucose Isomerase/Autocrine Motility Factor/Neuroleukin Complexed with Its Carbohydrate Phosphate Inhibitors Suggests Its Substrate/Receptor Recognition

Abstract

Phosphoglucose isomerase catalyzes the reversible isomerization of glucose 6-phosphate to fructose 6-phosphate. In addition, phosphoglucose isomerase has been shown to have functions equivalent to neuroleukin, autocrine motility factor, and maturation factor. Here we present the crystal structures of phosphoglucose isomerase complexed with 5-phospho-D-arabinonate and N-bromoacetylethanolamine phosphate at 2.5-and 2.3-Å resolution, respectively. The inhibitors bind to a region within the domains' interface and interact with a histidine residue (His 306 ) from the other subunit. We also demonstrated that the inhibitors not only affect the enzymatic activity of phosphoglucose isomerase, but can also inhibit the autocrine motility factor-induced cell motility of CT-26 mouse colon tumor cells. These results indicate that the substrate and the receptor binding sites of phosphoglucose isomerase and autocrine motility factor are located within close proximity to each other. Based on these two complex structures, together with biological and biochemical results, we propose a possible isomerization mechanism for phosphoglucose isomerase.Phosphoglucose isomerase (PGI) 1 (EC 5.3.1.9), a glycolytic enzyme, is an essential enzyme in all tissues. It interconverts glucose 6-phosphate and fructose 6-phosphate, hence plays a central role in both the glycolysis and the gluconeogenesis pathways. PGI deficiency in humans is an autosomal recessive genetic disorder that has the typical manifestation of nonspherocytic hemolytic anemia of variable clinical expression (1, 2). The serum activity of human PGI serves as a tumor marker in cancer patients (3, 4) and elevation in PGI activity is closely correlated with metastasis (5, 6). In addition to its essential role in carbohydrate metabolism in the cytoplasm, PGI also functions as neuroleukin (NLK) (7-9), autocrine motility factor (AMF) (10, 11), and maturation factor (MF) (12).NLK is a neurotrophic growth factor that promotes the survival of spinal and sensory neurons (13). Interestingly, PGI and NLK have previously been reported to have differential induction capabilities for certain neurons (9). AMF, a new class of cytokines, can stimulate cell migration in vitro and metastasis in vivo (10, 14 -16). Amino acid sequencing and immunological cross-reactivity experiments suggest that mouse AMF is identical or closely related to PGI/NLK (10). MF is capable of mediating the differentiation of human myeloid leukemic HL-60 cells to terminal monocytic cells, and apparently a high degree of homology exists between the MF of myeloid leukemia cells and PGI or NLK (12).It was previously suggested that PGI may recognize a sugarcontaining molecule(s) at the cell surface (7) and that NLK binds to the cell surface in a carbohydrate-dependent manner utilizing a PGI-like structure. Watanabe (10, 16) also pointed out that AMF (PGI/NLK/MF) may contain a PGI-like structure and initiates signal transduction by interacting with the carbohydrate side chains of the extracellular domain of the AMF receptor (AMF...

The crystal structure of rabbit phosphoglucose isomerase complexed with 5-phospho- d -arabinonohydroxamic acid

“…The new crystal structure provides better information about how the reaction intermediate is likely to bind in the active site than was seen with crystal structures of PGI͞5PAA complexes (41,43) and provides an insight into the mechanism of proton transfer between the O1 and O2 atoms of the intermediate. The most significant differences are in the positioning of the C1 and C2 region of the inhibitors, the region that corresponds to the double bond in the proposed cis-enediol(ate) catalytic intermediate.…”

“…Published PGI crystal structures include a partial structure from pig (39), structures from Bacillus stearothermophilus [unliganded (40) or complexed with 5-phospho-D-arabinonate (5PAA) (41) or N-bromoacetylethanolamine phosphate (41)], from rabbit [complexed with 6-phospho-D-gluconate (42), 5PAA (43), or the cyclic form of a substrate, F6P (44)], and from human [complexed with ␤-mercaptoethanol and a sulfate ion (7)]. …”

Isolation of Novel Animal Cell Lines Defective in Glycerolipid Biosynthesis Reveals Mutations in Glucose-6-phosphate Isomerase

“…An extracellular receptor for GPI/autocrine motility factor, gp78, has been identified (54). It has been proposed that GPI/autocrine motility factor binds to its receptor through its conserved active site or in a region close to the active site (55). Therefore, changes in the active site would most probably interfere with receptor binding.…”

Bifunctional Phosphoglucose/Phosphomannose Isomerases from the Archaea Aeropyrum pernix and Thermoplasma acidophilum Constitute a Novel Enzyme Family within the Phosphoglucose Isomerase Superfamily

“…PGI structures have been solved from a variety of mammalian sources and from B. stearothermophilus in native, inhibitor, and substrate (F6P)-bound forms (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). CD spectra analysis and secondary structure predictions suggest a similar fold of the PGI/PMI from A. pernix and T. acidophilum and e.g.…”