The interaction of FBPase with aldolase: a kinetic and fluorescence investigation on chicken muscle enzymes

Fructose-1,6-bisphosphatase: From a glucose metabolism enzyme to multifaceted regulator of a cell fate

Fructose-1,6-bisphosphatase (FBPase) is one of the ancient, evolutionarily conserved enzymes of carbohydrate metabolism. It has been described for a first time in 1943, however, for the next half a century mostly kinetic and structural parameters of animal FBPases have been studied. Discovery of ubiquitous expression of the muscle isozyme of FBPase, thus far considered to merely regulate glycogen synthesis from carbohydrate precursors, and its nuclear localisation in several cell types has risen new interest in the protein, resulting in numerous publications revealing complex functions/properties of FBPase. This review summarises the current knowledge of FBPase in animal cells providing evidence that the enzyme merits the name of moonlighting protein.

Cloning, expression, and partial characterization of FBPA from Schistosoma japonicum, a molecule on that the fluke may develop nutrition competition and immune evasion from human

Carbohydrate metabolism is the most important physiological process for Schistosoma japonicum which resides in host. However, as a key glycolytic enzyme in carbohydrate metabolism, fructose-1,6-bisphosphate aldolase (FBPA), there is no study on its enzymatic kinetics and antigenic peptides. Here, we report the gene cloning, expression, purification, and kinetics of the FBPA from S. japonicum (sjFBPA). After cloning, sjFBPA gene was introduced into pET-28a and transformed BL21, and a soluble His6-sjFBPA was expressed and purified successfully at the expected molecular mass of ~45 kDa. We first reported that the diversities in IGS regions and the features of residues position 346 and 357-362 of sjFBPA may be conferred either through conformational changes influencing easily the active site from a distance and/or causing the C-terminal region to interact directly with the active site, which lead His6-sjFBPA to exhibit a higher specific activity of 197.43 units/mg and degrades FBP with a typical substrate inhibition model and a higher efficiency of k cat  = 6261.3/s and K m  = 0.061 μM than human aldolases, which might be the strategy that S. japonicum gaining energy and surviving in its environment with low concentration of carbohydrate, and benefitting to get more metabolic substances for parasites in nutrition competition with their host. sjFBPA exhibits a high similarity of 81.46 % with that of hosts, especially in antigenic peptide regions, and 14 of 15 antigenic peptides of sjFBPA were conserved to those of human aldolase A, B, and/or C with high identity (17, 16, or 16 antigenic peptides, respectively), which may result in a molecular mimicry of FBPA with that of host, and an immune evasion from their hosts. This work would supply an experimental base for using FBPA to prevent the schistosomiasis in the future.

Kinetic properties of Pelophylax esculentus muscle FBPase

D-Fructose-1,6-bisphosphate 1-phosphohydrolase FBPase; [EC 3.1.3.11] was isolated from Pelophylax esculentus muscle in an electrophoretically homogeneous form with ca 30% yield. Its subunit molecular mass is ca 37 kDa. In this study, we determined the basic kinetic properties of the frog muscle enzyme. FBPase exhibited a maximum activity at pH 7.5. Like other FBPases the frog enzyme requires magnesium ions for its activity (K(a)=263 microM) and is activated by potassium ions (K(a)=63.6 microM). I(0.5) for calcium ion (91 microM) is 100 times higher than the corresponding value of mammalian muscle FBPase. K(s) for the substrate was 1.68 microM. Substrate excess inhibited the enzyme (K(si)=55 microM). AMP and fructose-2,6-bisphosphate (Fru-2,6P(2)) are potent inhibitors of frog muscle FBPase with I(0.5) of 0.2 microM and K(i) of 114 nM, respectively. Both inhibitors act synergistically on the frog muscle FBPase. In the presence of 0.05-0.5 microM of AMP, K(i) for Fru-2,6P(2) is 92 and 28 nM. I(0.5) for AMP for P. esculentus muscle FBPase is 55 times lower than the corresponding value for P. esculentus liver isozyme.

The human Werner syndrome protein stimulates repair of oxidative DNA base damage by the DNA glycosylase NEIL1

The mammalian DNA glycosylase, NEIL1, specific for repair of oxidatively damaged bases in the genome via the base excision repair pathway, is activated by reactive oxygen species and prevents toxicity due to radiation. We show here that the Werner syndrome protein (WRN), a member of the RecQ family of DNA helicases, associates with NEIL1 in the early damage-sensing step of base excision repair. WRN stimulates NEIL1 in excision of oxidative lesions from bubble DNA substrates. The binary interaction between NEIL1 and WRN (K(D) = 60 nM) involves C-terminal residues 288-349 of NEIL1 and the RecQ C-terminal (RQC) region of WRN, and is independent of the helicase activity WRN. Exposure to oxidative stress enhances the NEIL-WRN association concomitant with their strong nuclear co-localization. WRN-depleted cells accumulate some prototypical oxidized bases (e.g. 8-oxoguanine, FapyG, and FapyA) indicating a physiological function of WRN in oxidative damage repair in mammalian genomes. Interestingly, WRN deficiency does not have an additive effect on in vivo damage accumulation in NEIL1 knockdown cells suggesting that WRN participates in the same repair pathway as NEIL1.

Characterization of an Aldolase-binding Site in the Wiskott-Aldrich Syndrome Protein

The thrombospondin-related anonymous protein (TRAP) is an essential transmembrane molecule in Plasmodium sporozoites. TRAP displays adhesive motifs on the extracellular portion, whereas its cytoplasmic tail connects to actin via aldolase, thus driving parasite motility and host cell invasion. The minimal requirements for the TRAP binding to aldolase were scanned here and found to be shared by different human proteins, including the Wiskott-Aldrich syndrome protein (WASp) family members. In vitro and in vivo binding of WASp members to aldolase was characterized by biochemical, deletion mapping, mutagenesis, and co-immunoprecipitation studies. As in the case of TRAP, the binding of WASp to aldolase is competitively inhibited by the enzyme substrate/products. Furthermore, TRAP and WASp, but not other unrelated aldolase binders, compete for the binding to the enzyme in vitro. Together, our results define a conserved aldolase binding motif in the WASp family members and suggest that aldolase modulates the motility and actin dynamics of mammalian cells. These findings along with the presence of similar aldolase binding motifs in additional human proteins, some of which indeed interact with aldolase in pull-down assays, suggest supplementary, non-glycolytic roles for this enzyme.

Localization of chicken muscle FBPase in cardiomyocyte nuclei

Fructose 1,6-bisphosphatase (FBPase; EC 3.1.3.11) localization in cardiomyocyte nuclei has recently been investigated in mammals [FEBS Lett. 539 (2003) 51]. In this study, nuclear localization of FBPase in the cardiac muscle of the chicken was studied by immunohistochemistry and other methods. A result of the electron microscopic investigation was confirmed by immunoblotting analysis. Using MALDI Q-TOF mass spectrometry and Mascot program, the nuclear FBPase was identified as muscle chicken FBPase. FBPase activity in isolated cardiomyocyte nuclei was 5.9 mU/g. Nuclear FBPase was strongly inhibited by allosteric inhibitor AMP. I(0.5) for AMP was 0.16 microM and was the same as for the purified chicken muscle enzyme.

F-actin, beta-tubulin, aldolase, and fructose-1,6-bisphosphatase in heteropteran ovarioles--I. Immunocytochemical investigations of whole-mounted ovarioles

The distribution of F-actin, beta-tubulin, aldolase, and fructose-1,6-bisphosphatase (FBPase) in ovarioles of four heteropteran species (Ilyocoris cimicoides, Coreus marginatus, Lygus pratensis, and Notostira elongata) was investigated biochemically and immunocytochemically. Aldolase was found to be uniformly distributed in the cytoplasm of trophocytes and follicular cells, with the highest concentration in prefollicular cells. Its concentration in follicular cells increased during differentiation and reached a peak in ovarian follicles at the stage of late choriogenesis. FBPase was observed in the cytoplasm (weak reaction) and on cell borders (strong reaction) of both germ line and somatic cells. No FBPase or aldolase signal was observed on the F-actin trophic core mesh or on stress fibers.

Enzyme co-localization in pea leaf chloroplasts: glyceraldehyde-3-P dehydrogenase, triose-P isomerase, aldolase and sedoheptulose bisphosphatase

Nearest neighbor analysis of immunocytolocalization experiments indicates that the enzymes glyceraldehyde-3-P dehydrogenase, triose-P isomerase and aldolase are located close to one another in the pea leaf chloroplast stroma, and that aldolase is located close to sedoheptulose bisphosphatase. Direct transfer of the triose phosphates between glyceraldehyde-3-P dehydrogenase and triose-P isomerase, and from glyceraldehyde-3-P dehydrogenase and triose-P isomerase to aldolase, is then a possibility, as is direct transfer of sedoheptulose bisphosphate from aldolase to sedoheptulose bisphosphatase. Spatial organization of these enzymes may be important for efficient CO(2) fixation in photosynthetic organisms. In contrast, there is no indication that fructose bisphosphatase is co-localized with aldolase, and direct transfer of fructose bisphosphate from aldolase to fructose bisphosphatase seems unlikely.