A comparative study of biochemical and immunological properties of triosephosphate isomerase from Taenia solium and Sus scrofa

We produced the Taenia solium triosephosphate isomerase (TPI) in Escherichia coli and compared its biochemical and immunological properties with those of the commercial TPI from Sus scrofa. Taenia solium TPI is a homodimer composed of two 27-kDa monomers, with a specific activity of 5,683 U/mg and a Km value of 0.758, and S. scrofa TPI is also dimeric with similar monomeric molecular weight, specific activity of 4,227 U/mg, and a Km value of 0.51. The catalytic parameters for the isomerization of glyceraldehyde 3-phosphate, affinity between TPI monomers, and kinetic thermal denaturation and inactivation were similar for both enzymes. Anti-T. solium TPI antibodies cross-react weakly with Schistosoma mansoni TPI but do not cross-react with S. scrofa, human, or protozoan TPIs. These antibodies inhibited T. solium TPI activity but did not affect S. scrofa enzymatic activity. Immunizations with 1 microg of the T. solium TPI reduced 52% of cysticerci in a mouse-Taenia crassiceps model 1 mo after challenge. Our findings show that T. solium and S. scrofa TPIs possess similar biochemical and enzymatic properties but do not share immunological properties because anti-T. solium TPI antibodies did not recognize S. scrofa TPI. Inhibition of enzyme activity by anti-TPI antibodies suggests that they can be used as inhibitors of the enzyme.     

Cytosolic triosephosphate isomerase is a single gene in rice.

A cDNA clone encoding rice (Oryza sativa L.) cytosolic triosephosphate isomerase (TPI), an important glycolytic enzyme, was isolated and characterized. The clone (pRTPI-6) contains an open reading frame of 759 base pairs, encoding a polypeptide chain of 253 amino acid residues (M(r) 27,060). The identity of this clone was defined by its high homology (85% nucleotide sequence and 89% amino acid sequence identical match) with a maize mRNA sequence encoding the cytosolic TPI and with TPIs from other species. Genomic DNA blot analysis using the cDNA as a probe showed that the cytosolic TPI gene is present as a single copy per haploid rice genome, as opposed to that found in maize, in which multiple TPI gene copies exist. A single TPI mRNA species of about 1100 nucleotides was detected by gel blot hybridization analysis of RNA isolated from root, culm, and leaf tissues, indicating that its expression is ubiquitous. Based on sequence comparison and molecular analysis, we propose that the chloroplast-located TPI may be encoded by divergent structural nuclear genes in rice.     

Purification of triosephosphate isomerase and isolation of its gene from the mosquito Culex tarsalis

The enzyme triosephosphate isomerase (TPI) was purified to homogeneity from the mosquito Culex tarsalis. Anti-C. tarsalis TPI antibodies cross-reacted with TPIs from other organisms but bands on western blots were most intense with proteins from closely related Dipterans. Using a degenerate primer corresponding to the amino-terminal sequence of the protein in a polymerase chain reaction (PCR), a cDNA corresponding to the TPI gene (Tpi) was isolated and sequenced. Subsequently, a genomic sequence including 305 bp to the 5′-end of the coding sequence was obtained. Comparison of C. tarsalis Tpi to that of Drosophila melanogaster revealed that although the two genes had little similarity in the intron and 5′ flanking sequences, they were highly similar (73% identity) in their coding sequence. The rate of synonymous substitution in insect genes may be slower than that of vertebrates, but the nonsynonymous substitution rate, and hence the rate of TPI evolution, appears to be faster in insects than in vertebrates.     

Bacterial expression and characterization of functional recombinant triosephosphate isomerase from Schistosoma japonicum

The dimeric enzyme triosephosphate isomerase (TPI) converts glyceraldehyde-3-phosphate to dehydroxyacetone phosphate, a key reaction in glycolysis. Previous studies of the native enzyme in the human blood-flukes belonging to the genus Schistosoma have indicated that TPI is a promising anti-schistosome vaccine antigen. However, a recombinant form of the enzyme is required as an alternative to the impractical option of using biochemically purified TPI obtained from worm tissue for large-scale vaccine use. We previously cloned and sequenced a full-length cDNA encoding the TPI of the Asian (Chinese strain) schistosome Schistosoma japonicum (SjcTPI). We now report very high level bacterial expression of this cDNA and the subsequent purification of the recombinant protein to >98% homogeneity under nondenaturing conditions. The recombinant SjcTPI (re-SjcTPI) was shown to be enzymatically active with a specific activity of 7687 units/mg protein, an activity higher than that of commercially obtained porcine TPI tested concurrently under the same assay conditions. The K(m) value for the re-SjcTPI using glyceraldehyde-3-phosphate as substrate was 406.7 microM, which is similar to the K(m) values reported for the yeast enzyme and various mammalian TPIs. With the availability of substantial amounts of enzymatically active and readily purified re-SjcTPI made in bacteria we can now test whether the recombinant protein can induce a similar level of protection in vaccination/challenge experiments as the native, biochemically purified enzyme.     

Triosephosphate isomerase deficiency: New insights into an enigmatic disease

The triosephosphate isomerase (TPI) functions at a metabolic cross-road ensuring the rapid equilibration of the triosephosphates produced by aldolase in glycolysis, which is interconnected to lipid metabolism, to glycerol-3-phosphate shuttle and to the pentose phosphate pathway. The enzyme is a stable homodimer, which is catalytically active only in its dimeric form. TPI deficiency is an autosomal recessive multisystem genetic disease coupled with hemolytic anemia and neurological disorder frequently leading to death in early childhood. Various genetic mutations of this enzyme have been identified; the mutations result in decrease in the catalytic activity and/or the dissociation of the dimers into inactive monomers. The impairment of TPI activity apparently does not affect the energy metabolism at system level; however, it results in accumulation of dihydroxyacetone phosphate followed by its chemical conversion into the toxic methylglyoxal, leading to the formation of advanced glycation end products. By now, the research on this disease seems to enter a progressive stage by adapting new model systems such as Drosophila, yeast strains and TPI-deficient mouse, which have complemented the results obtained by prediction and experiments with recombinant proteins or erythrocytes, and added novel data concerning the complexity of the intracellular behavior of mutant TPIs. This paper reviews the recent studies on the structural and catalytic changes caused by mutation and/or nitrotyrosination of the isomerase leading to the formation of an aggregation-prone protein, a characteristic of conformational disorders.     

意大利蜜蜂丙糖磷酸异构酶基因的克隆及其原核表达与纯化

从意大利蜜蜂Apis mellifera ligustica的肌肉组织中提取总RNA,采用RT-PCR的方法克隆蜜蜂第16号染色体上的丙糖磷酸异构酶基因的cDNA序列,将测序结果(GenBank登录号EU76098)与推导的氨基酸序列分别与GenBank中的其他物种进行同源比对分析。结果表明,该基因全长744bp,为完整的阅读框,编码247个氨基酸,成熟蛋白的理论分子量为26.89kD。比对结果显示AmTPI与家蚕、德国小镰、黄粉虫、丽蝇蛹集金小蜂、水稻等物种的基因相似性达69%以上,蛋白相似性达59%以上。将目的基因克隆到pGEX-4T-2融合表达载体上,并在大肠杆菌中得到成功表达,4h的表达量为总蛋白的42.1%。为了进一步探讨产物的酶学特性,实验还对表达产物进行纯化与浓缩。实验还构建增强型荧光真核表达质粒,为进一步研究AmTPI在真核细胞中的表达情况奠定基础。     

Chloroplast and cytosolic triosephosphate isomerases from spinach: purification,microsequencing and cDNA cloning of the chloroplast enzyme

Chloroplast and cytosolic triosephosphate isomerases from spinach were separated and purified to homogeneity. Both enzymes were partially sequenced by Edman degradation. Using degenerate primers designed against the amino acid sequences, a homologous probe for the chloroplast enzyme was amplified and used to isolate several full-size cDNA clones. Chloroplast triosephosphate isomerase is encoded by a single gene in spinach. Analysis of the chloroplast cDNA sequence in the context of its homologues from eukaryotes and eubacteria reveals that the gene arose through duplication of its pre-existing nuclear counterpart for the cytosolic enzyme during plant evolution.Abbreviations TPI triosephosphate isomerase - PEG polyethylene glycol - cp plastid - c cytosolic - SDS sodium dodecyl sulphate - PAGE polyacrylamide gel electrophoresis - PVP polyvinylpyrrolidone - PCR polymerase chain reaction - PGK 3-phosphoglycerate kinase     

Nucleotide sequence of the triosephosphate isomerase gene from Aspergillus nidulans: implications for a differential loss of introns

A functional cDNA from Aspergillus nidulans encoding triosephosphate isomerase (TPI) was isolated by its ability to complement a tpi1 mutation in Saccharomyces cerevisiae. This cDNA was used to obtain the corresponding gene, tpiA. Alignment of the cDNA and genomic DNA nucleotide sequences indicated that tpiA contains five introns. The intron positions in the tpiA gene were compared with those in the TPI genes of human, chicken, and maize. One intron is present at an identical position in all four organisms, two other introns are located in similar positions in A. nidulans and maize, and the remaining two introns are unique to A. nidulans. These Aspergillus-specific introns are located in regions of the protein that were predicted to be interrupted by introns based on analysis of a Go plot of chicken TPI. These comparisons are discussed in relation to the evolution of introns within TPI genes.     

Bacterial Expression and Characterization of Functional Recombinant Triosephosphate Isomerase from Schistosoma japonicum

The dimeric enzyme triosephosphate isomerase (TPI) converts glyceraldehyde-3-phosphate to dehydroxyacetone phosphate, a key reaction in glycolysis. Previous studies of the native enzyme in the human bloodflukes belonging to the genus Schistosoma have indicated that TPI is a promising anti-schistosome vaccine antigen. However, a recombinant form of the enzyme is required as an alternative to the impractical option of using biochemically purified TPI obtained from worm tissue for large-scale vaccine use. We previously cloned and sequenced a full-length cDNA encoding the TPI of the Asian (Chinese strain) schistosome Schistosoma japonicum (SjcTPI). We now report very high level bacterial expression of this cDNA and the subsequent purification of the recombinant protein to >98% homogeneity under nondenaturing conditions. The recombinant SjcTPI (re-SjcTPI) was shown to be enzymatically active with a specific activity of 7687 units/mg protein, an activity higher than that of commercially obtained porcine TPI tested concurrently under the same assay conditions. The K_m value for the re-SjcTPI using glyceraldehyde-3-phosphate as substrate was 406.7 μM, which is similar to the K_m values reported for the yeast enzyme and various mammalian TPIs. With the availability of substantial amounts of enzymatically active and readily purified re-SjcTPI made in bacteria we can now test whether the recombinant protein can induce a similar level of protection in vaccination/challenge experiments as the native, biochemically purified enzyme.     

Drosophila model of human inherited triosephosphate isomerase deficiency glycolytic enzymopathy

Heritable mutations, known as inborn errors of metabolism, cause numerous devastating human diseases, typically as a result of a deficiency in essential metabolic products or the accumulation of toxic intermediates. We have isolated a missense mutation in the Drosophila sugarkill (sgk) gene that causes phenotypes analogous to symptoms of triosephosphate isomerase (TPI) deficiency, a human familial disease, characterized by anaerobic metabolic dysfunction resulting from pathological missense mutations affecting the encoded TPI protein. In Drosophila, the sgk gene encodes the glycolytic enzyme TPI. Our analysis of sgk mutants revealed TPI impairment associated with reduced longevity, progressive locomotor deficiency, and neural degeneration. Biochemical studies demonstrate that mutation of this glycolytic enzyme gene does not result in a bioenergetic deficit, suggesting an alternate cause of enzymopathy associated with TPI impairment.     

Evidence for a period of directional selection following gene duplication in a neurally expressed locus of triosephosphate isomerase

A striking correlation between neural expression and high net negative charge in some teleost isozymes led to the interesting, yet untested, suggestion that negative charge represents an adaptation (via natural selection) to the neural environment. We examine the evolution of the triosephosphate isomerase (TPI) gene family in fishes for periods of positive selection. Teleost fish express two TPI proteins, including a generally expressed, neutrally charged isozyme and a neurally expressed, negatively charged isozyme; more primitive fish express only a single, generally expressed TPI isozyme. The TPI gene phylogeny constructed from sequences isolated from two teleosts, a single acipenseriform, and other TPI sequences from the databases, supports a single gene duplication event early in the evolution of bony fishes. Comparisons between inferred ancestral TPI sequences indicate that the neural TPI isozyme evolved through a period of positive selection resulting in the biased accumulation of negatively charged amino acids. Further, the number of nucleotide changes required for the observed amino acid substitutions suggests that selection acted on the overall charge of the protein and not on specific key amino acids.     

The evolutionary origins and catalytic importance of conserved electrostatic networks within TIM-barrel proteins

Conservation of function is the basic tenet of protein evolution. Conservation of key electrostatic properties is a frequently employed mechanism that leads to conserved function. In a previous report, we identified several conserved electrostatic properties in four protein families and one functionally diverse enzyme superfamily. In this report, we demonstrate the evolutionary and catalytic importance of electrostatic networks in three ubiquitous metabolic enzymes: triosephosphate isomerase, enolase, and transaldolase. Evolutionary importance is demonstrated using phylogenetic motifs (sequence fragments that parallel the overall familial phylogeny). Phylogenetic motifs frequently correspond to both catalytic residues and conserved interactions that fine-tune catalytic residue pKa values. Further, in the case of triosephosphate isomerase, quantitative differences in the catalytic Glu169 pKa values parallel subfamily differentiation. Finally, phylogenetic motifs are shown to structurally cluster around the active sites of eight different TIM-barrel families. Depending upon the mechanistic requisites of each reaction catalyzed, interruptions to the canonical fold may or may not be identified as phylogenetic motifs.     

Rapid isolation of triosephosphate isomerase utilizing high-performance liquid chromatography

A new method for the isolation of homogeneous triosephosphate isomerase (TPI, EC 5.3.1.1) has been developed. The method utilizes high-performance liquid chromatography on DEAE 5PW and Hydrophase-polyethyleneimine columns, which results in the rapid isolation and essentially quantitative recovery of the enzyme. The procedure is superior to previous methods with respect to specificity, recovery, and time. In addition, this rapid process minimizes the potential for postsynthetic modifications of the protein. Milligram quantities of TPI can be isolated from 100 g of tissue.     

The hyperthermophilic bacterium Thermotoga neapolitana possesses two isozymes of the 3-phosphoglycerate kinase/triosephosphate isomerase fusion protein

Abstract The phosphoglycerate kinase ( pgk ), triosephosphate isomerase ( tpi ), and enolase ( eno ) genes from Thermotoga neapolitana have been cloned and expressed in Escherichia coli . In high copy number, the pgk gene complemented an E. coli pgk ⁻ strain. In T. neapolitana , the pgk and tpi genes appear to be fused and eno is near those genes. Like T. maritima , T. neapolitana produces phosphoglycerate kinase as both an individual enzyme and a fusion protein with triosephosphate isomerase, and triosephosphate isomerase activity is not found without associated phosphoglycerate kinase activity. Unlike T. maritima , which forms only a 70-kDa fusion protein, T. neapolitana expresses both 73-kDa and 81-kDa isozymes of this fusion protein. These isozymes are present in both T. neapolitana cells and in E. coli cells expressing T. neapolitana genes.     

Characterization of the functional gene and several processed pseudogenes in the human triosephosphate isomerase gene family.

The functional gene and three intronless pseudogenes for human triosephosphate isomerase were isolated from a recombinant DNA library and characterized in detail. The functional gene spans 3.5 kilobase pairs and is split into seven exons. Its promoter contains putative TATA and CCAAT boxes and is extremely rich in G and C residues (76%). The pseudogenes share a high degree of homology with the functional gene but contain mutations that preclude the synthesis of an active triosephosphate isomerase enzyme. Sequence divergence calculations indicate that these pseudogenes arose approximately 18 million years ago. We present evidence that there is a single functional gene in the human triosephosphate isomerase gene family.     

Manipulation of endogenous trypsin proteinase inhibitor production in Nicotiana attenuata demonstrates their function as antiherbivore defenses

Evidence for the in planta defensive function of trypsin protease inhibitors (TPIs) comes from observations of enhanced herbivore resistance after heterologous TPI expression or the manipulation of signal cascades that activate numerous defense responses, including TPI production; no studies have altered the expression of an endogenous pi gene to examine defensive function. We isolated two genes with seven- and six-repeat TPI domains from Nicotiana attenuata from the potato (Solanum tuberosum) PI-II family. To determine whether endogenous TPIs in N. attenuata function defensively against the native herbivores, hornworm (Manduca sexta) and mirids (Tupiocoris notatus), we expressed 175 bp of the seven-domain pi from N. attenuata in an antisense orientation in a TPI-producing genotype to reduce TPI expression and expressed the full-length seven-domain pi in a sense orientation under control of a constitutive promoter to restore TPI activity in a natural genotype from Arizona unable to produce TPIs. Constitutive and inducible TPI production in two antisense lines were diminished by 80% to 90% and 33% to 52%, respectively, and sense expression restored 67% of the activity found in the TPI-producing genotype after caterpillar attack in the TPI-deficient A genotype. Hornworm larvae fed on genotypes with low or no TPI activity grew faster, had higher survivorship, and produced heavier pupae than those that fed on genotypes with high TPI activity. T. notatus showed higher preference for genotypes with low or no TPI activity than for genotypes with high TPI levels. We conclude that endogenous TPIs are an effective defense against these native herbivores.     

xylA cloning and sequencing and biochemical characterization of xylose isomerase from Thermotoga neapolitana.

The xylA gene coding for xylose isomerase from the hyperthermophile Thermotoga neapolitana 5068 was cloned, sequenced, and expressed in Escherichia coli. The gene encoded a polypeptide of 444 residues with a calculated molecular weight of 50,892. The native enzyme was a homotetramer with a molecular weight of 200,000. This xylose isomerase was a member of the family II enzymes (these differ from family I isomerases by the presence of approximately 50 additional residues at the amino terminus). The enzyme was extremely thermostable, with optimal activity above 95 degrees C. The xylose isomerase showed maximum activity at pH 7.1, but it had high relative activity over a broad pH range. The catalytic efficiency (kcat/Km) of the enzyme was essentially constant between 60 and 90 degrees C, and the catalytic efficiency decreased between 90 and 98 degrees C primarily because of a large increase in Km. The T. neapolitana xylose isomerase had a higher turnover number and a lower Km for glucose than other family II xylose isomerases. Comparisons with other xylose isomerases showed that the catalytic and cation binding regions were well conserved. Comparison of different xylose isomerase sequences showed that numbers of asparagine and glutamine residues decreased with increasing enzyme thermostability, presumably as a thermophilic strategy for diminishing the potential for chemical denaturation through deamidation at elevated temperatures.     

Plant triose phosphate isomerase isozymes : purification, immunological and structural characterization, and partial amino Acid sequences

We report the first complete purifications of the cytosolic and plastid isozymes of triose phosphate isomerase (TPI; EC 5.3.1.1) from higher plants including spinach (Spinacia oleracea), lettuce (Lactuca sativa), and celery (Apium graveolens). Both isozymes are composed of two isosubunits with approximate molecular weight of 27,000; in spinach and lettuce the plastid isozyme is 200 to 400 larger than the cytosolic isozyme. The two isozymes, purified from lettuce, had closely similar amino acid compositions with the exception of methionine which was four times more prevalent in the cytosolic isozyme. Partial amino acid sequences from the N-terminus were also obtained for both lettuce TPIs. Nine of the 13 positions sequenced in the two proteins had identical amino acid residues. The partial sequences of the plant proteins showed high similarity to previously sequenced animal TPIs. Immunological studies, using antisera prepared independently against the purified plastid and cytosolic isozymes from spinach, revealed that the cytosolic isozymes from a variety of species formed an immunologically distinct group as did the plastid isozymes. However, both plastid and cytosolic TPIs shared some antigenic determinants. The overall similarity of the two isozymes and the high similarity of their partial amino acid sequences to those of several animals indicate that TPI is a very highly conserved protein.     

Compartment-specific isoforms of TPI and GAPDH are imported into diatom mitochondria as a fusion protein: evidence in favor of a mitochondrial origin of the eukaryotic glycolytic pathway

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and triosephosphate isomerase (TPI) are essential to glycolysis, the major route of carbohydrate breakdown in eukaryotes. In animals and other heterotrophic eukaryotes, both enzymes are localized in the cytosol; in photosynthetic eukaryotes, GAPDH and TPI exist as isoenzymes that function in the glycolytic pathway of the cytosol and in the Calvin cycle of chloroplasts. Here, we show that diatoms--photosynthetic protists that acquired their plastids through secondary symbiotic engulfment of a eukaryotic rhodophyte--possess an additional isoenzyme each of both GAPDH and TPI. Surprisingly, these new forms are expressed as an TPI-GAPDH fusion protein which is imported into mitochondria prior to its assembly into a tetrameric bifunctional enzyme complex. Homologs of this translational fusion are shown to be conserved and expressed also in nonphotosynthetic, heterokont-flagellated oomycetes. Phylogenetic analyses show that mitochondrial GAPDH and its N-terminal TPI fusion branch deeply within their respective eukaryotic protein phylogenies, suggesting that diatom mitochondria may have retained an ancestral state of glycolytic compartmentation that existed at the onset of mitochondrial symbiosis. These findings strongly support the view that nuclear genes for enzymes of glycolysis in eukaryotes were acquired from mitochondrial genomes and provide new insights into the evolutionary history (host-symbiont relationships) of diatoms and other heterokont-flagellated protists.     

Structure and Stability of the Dimeric Triosephosphate Isomerase from the Thermophilic Archaeon Thermoplasma acidophilum

Thermoplasma acidophilum is a thermophilic archaeon that uses both non-phosphorylative Entner-Doudoroff (ED) pathway and Embden-Meyerhof-Parnas (EMP) pathway for glucose degradation. While triosephosphate isomerase (TPI), a well-known glycolytic enzyme, is not involved in the ED pathway in T. acidophilum, it has been considered to play an important role in the EMP pathway. Here, we report crystal structures of apo- and glycerol-3-phosphate-bound TPI from T. acidophilum (TaTPI). TaTPI adopts the canonical TIM-barrel fold with eight α-helices and parallel eight β-strands. Although TaTPI shares ~30% sequence identity to other TPIs from thermophilic species that adopt tetrameric conformation for enzymatic activity in their harsh physiological environments, TaTPI exists as a dimer in solution. We confirmed the dimeric conformation of TaTPI by analytical ultracentrifugation and size-exclusion chromatography. Helix 5 as well as helix 4 of thermostable tetrameric TPIs have been known to play crucial roles in oligomerization, forming a hydrophobic interface. However, TaTPI contains unique charged-amino acid residues in the helix 5 and adopts dimer conformation. TaTPI exhibits the apparent T_d value of 74.6°C and maintains its overall structure with some changes in the secondary structure contents at extremely acidic conditions (pH 1–2). Based on our structural and biophysical analyses of TaTPI, more compact structure of the protomer with reduced length of loops and certain patches on the surface could account for the robust nature of Thermoplasma acidophilum TPI.