Molecular cloning and characterization of cDNA encoding a ubiquitin-conjugating enzyme from Clonorchis sinensis

Identification and biochemical characterization of adenylate kinase 1 from Clonorchis sinensis

Adenylate kinase 1 is responsible for the conversion of AMP into ADP involved in purine metabolism. In the present study, adenylate kinase 1 gene (CsADK1) was isolated from an adult cDNA library of Clonorchis sinensis, and the recombinant protein was expressed in Escherichia coli. Bioinformatics analysis implied that the putative protein contained 197 amino acids, and some residues in conservative binding sites of CsADK1 were substituted. The structure modeling analysis showed that CsADK1 was composed of a core domain, an NMP-binding domain, and a LID domain, which was just a small loop. It demonstrated that CsADK1 was a short isoform of ADKs. Moreover, CsADK1 was identified as an excretory/secretory product by western blot analysis. Real-time quantitative PCR showed that expression level of CsADK1 at the stage of excysted metacercaria was higher than those of adult worm (18.8-folds, P<0.01), metacercariae (1.5-folds, P<0.01), and eggs (5.6-folds, P<0.01). In addition, histochemistry analysis showed that CsADK1 was extensively distributed in metacercariae and in the vitellaria and eggs of adult worms. The Km and Vmax value for substrate ADP were 2.2 mM and 0.9 mM/min, respectively. The optimal temperature and pH value were 37 °C and from 7.5 to 8.0, respectively. The enzyme activity was highly dependent on Mg2+, and the optimal concentration of Mg2+ was 2 mM. However, the enzyme activity was slightly activated by Ca2+, and Mn2+ has no effect on activity. For monovalent ions, activity was highly activated by K+ and NH4+, but slightly by Li+. Taken together, CsADK1 was a metal ion-dependent enzyme involved in purine metabolism, which was important for development and reproduction, and might be a potential candidate for drug target for clonorchiasis.

Characterization of a Moniezia expansa ubiquitin-conjugating enzyme E2 cDNA

Ubiquitin and other ubiquitin-like proteins play important roles in post-translational modification. They are phylogenetically well-conserved in eukaryotes. Here we report a new ubiquitin-conjugating enzyme E2 cDNA, which containing a ubiquitin-conjugating enzyme UBCc-domain named UBE2AM. Its cDNA is 899 base pairs in length and contains an open reading frame from nucleotide 171 to 632 encoding 153 amino acids. The result of real time RT-PCR showed that UBEA2 M is expressed in most of M. expansa proglottides and over-expressed in the mature proglottides. Comparison of predicted UBE2AM with UBCc (protein) homologues/orthologous from other species revealed identities between species varying from 97.5 to 99.4% at the amino acid level. Phylogenetic analysis showed the UBE2AM is a member of the eukaryotic UBCc superfamily, which have diverged from a common ancestor and the gene is clustered in the same group with the ubiquitin-conjugating enzyme E2A-like protein from Taenia asiatica.

A novel tegumental protein 31.8 kDa of Clonorchis sinensis: sequence analysis, expression, and immunolocalization

The complementary DNA (cDNA) plasmid libraries of adult worm, metacercariae and egg of Clonorchis sinensis (C. sinensis) were constructed for researches on genomics and proteomics of C. sinensis. The full-length cDNA sequence encoding tegumental protein 31.8 kDa (CsTP31.8) was identified from the adult cDNA library. The cDNA sequence has been submitted to the GeneBank Database with accession number ABK60086. This novel cDNA sequence contains 828 bp with a putative open reading frame of 275 amino acids. The deduced amino acid sequence shows identity to membrane-associate antigens or tegumental antigens of other species. There were conserved calcium-binding EF hand and dynein light chain type 1 in the sequence. CsTP31.8 transcripts were detected in cDNA libraries of adult worm and metacercariae but not in that of egg. Recombinant CsTP31.8 was expressed and purified from Escherichia coli BL21 (DE3). CsTP31.8 was immunolocalized at the tegument of adult C. sinensis by using antirecombinant CsTP31.8 sera.

Molecular cloning and characterization of a phosphoglycerate mutase gene from Clonorchis sinensis

Phosphoglycerate mutase (PGM) is a widely distributed glycolytic enzyme. Two known distinct classes of PGM enzymes were identified, a cofactor-dependent one (dPGM) and a cofactor-independent one (iPGM). A complementary DNA (cDNA) encoding a PGM was cloned from a Clonorchis sinensis cDNA library by large-scale sequencing. This new cDNA contains 955 bp with a putative open reading frame of 256 amino acids, which has a high homology with dPGMs from a number of species. The putative peptide was produced in E. coli and was purified to electrophoretic homogeneity. Enzymatic assays showed that the product of this gene could catalyze the conversion of 3-phosphoglycerate to 2-phosphoglycerate when the cofactor was present and the enzyme activities could be inhibited by vanadate.

Clonorchis sinensis: molecular cloning and functional expression of a novel cytosolic glutathione transferase

Glutathione transferases (GSTs) represent a large family of enzymes. In the high throughput sequencing of the cDNA library constructed from the adult stage of Clonorchis sinensis (Cs), we isolate another cDNA clone encoding a novel cytosolic GST enzyme. To discriminate with our former reported CsGST, we designated this GST as CsGST1. This new cDNA contains 744 bp with a putative open reading frame of 213 amino acids. The deduced amino acid sequence exhibits 88% identity to Opisthorchis viverrini 28GST (Ov28GST), 60 and 52% identity to C. sinensis cytosolic 28-kDa GST (Cs28GST) and CsGST, respectively. The CsGST1 was expressed in Escherichia coli BL21(DE3) as a His-tag fusion protein and was purified by Ni-NTA agarose. The recombinant CsGST1 showed moderate GST activity of 0.79 U mg(-1). The average K (m) of the CsGST1 for 1-chloro-2, 4-dinitrobenzene is 150 microM. Cibacron blue F3GA and albendazole inhibited the CsGST1 activity with average IC(50) values of 9.1 and 265.4 muM, respectively. The nucleotide sequence reported in this paper was submitted to the GenBank Database with accession number DQ342327.

Molecular cloning and characterization of cDNA encoding a novel cytosolic glutathione transferase from Clonorchis sinensis

Glutathione transferases (GSTs) are a group of multifunction isoenzymes coded by many genes. A cDNA encoding a novel cytosolic GST enzyme was cloned from a Clonorchis sinensis (Cs) adult worm cDNA library by large-scale sequencing. This new cDNA contains 786 bp with a putative open reading frame of 212 amino acids. The deduced amino acid sequence exhibits 61% identity to C. sinensis cytosolic 28-kDa GST. Recombinant CsGST was overexpressed in Escherichia coli BL21(DE3) and was purified by Ni-NTA Agarose. Enzymatic assays showed that the recombinant CsGST had a high activity of 22.7 U mg(-1). The average K (m) of the CsGST for 1-chloro-2,4-dinitrobenzene is 111 microM. Cibacron blue F3GA and albendazole inhibited the CsGST activity with respective average IC(50) of 1.1 and 247.1 microM. It provides a model for the structure and physiological function analysis on CsGST. The nucleotide sequence reported in this paper has been submitted to the GenBank Database with accession number DQ179264.

Clonorchiasis: an update

Clonorchis sinensis, the Chinese or oriental liver fluke, is an important human parasite and is widely distributed in southern Korea, China (including Taiwan), Japan, northern Vietnam and the far eastern part of Russia. Clonorchiasis occurs in all parts of the world where there are Asian immigrants from endemic areas. The human and animal reservoir hosts (dogs, pigs, cats and rats) acquire the infection from the ingestion of raw fish containing infectious metacercariae. The first intermediate snail hosts are mainly species of Parafossarulus and Bithynia. Numerous species of freshwater fish serve as the second intermediate hosts of C. sinensis. Extensive studies of clonorchiasis during several decades in Japan, Korea, China and other countries have shown much progress in proving its morphological features including ultrastructure, biology, pathogenesis, epidemiology, clinical manifestations and chemotherapy. The present review deals with mainly current results obtained on the epidemiological, pathological and clinical aspects, as well as control measures in endemic areas. As for the complications of clonorchiasis, formation of calculi in the intrahepatic biliary passages is one of the most characteristic pathological features. It is sometimes accompanied by suppurative cholangitis, cholecystitis, cholangiohepatitis and ultimately can cause cholangiocarcinoma. Experimental results on the relationship to the occurrence of cholangiocarcinoma are presented. Clinical diagnosis by radiological findings including cholangiography, sonography and computerized tomography as well as magnetic resonance imaging for biliary or pancreatic ducts are outlined. Current studies on immunology and molecular biology of C. sinensis were introduced. Praziquantel is the drug of choice for clonorchiasis. The most effective regimen is 25 mg kg(-1) three times daily (total dose, 75 mg kg(-1)) administered orally at 5- to 6-h intervals over a single day. Prevention and control measures are also discussed.