title: Cloning and characterization of a novel enzyme: tyrosine hydroxylase from Schistosoma japonicum.
abstract: Catecholamines, such as dopamine and noradrenaline, play important roles as neuromuscular transmitters and modulators in all parasitic helminthes, including Schistosoma japonicum. S. japonicum tyrosine hydroxylase (SjTH) was amplified by rapid amplification of cDNA ends polymerase chain reaction that shows strong homology to Schistosoma mansoni tyrosine hydroxylase, the enzyme that catalyzes the first and rate-limiting step in the biosynthesis of catecholamines. The SjTH transcripts encoded the protein of 463 amino acids and a predicted size of 54 kDa. Purified recombinant SjTH as an N-terminal histidine fusion protein expressed in Escherichia coli showed catalytic activity that was confirmed with (3)H tyrosine uptake. The purified enzyme was found to have the same absolute requirement for a tetrahydrobiopterin cofactor and similar sensitivity to be inhibited by high concentration of the substrate, tyrosine, as the mammalian enzyme. Also, purified SjTH showed characteristic inhibition by catecholamine products. The phosphorylated peptide from SjTH could interact with Sj14-3-3 signal protein. This evidence indicates that SjTH encodes a functional tyrosine hydroxylase that has catalytic properties similar to those of the mammalian hosts' enzyme, and its catalytic activity could be regulated by a phosphorylated or dephosphorylated form. This demonstration of SjTH further suggests that the parasites have the enzymatic capacity to synthesize catecholamines endogenously.
authors.affiliation: Institute of Clinical Pharmacology, Anhui Medical University, The Key Laboratories of Zoonoses and Pathogen Biology, Anhui, Hefei, 230032 Anhui Province, China.
authors.forename: Yuansheng
authors.initials: Y
authors.lastname: Hu
authors.forename: Dujuan
authors.initials: D
authors.lastname: Shi
authors.forename: Qingli
authors.initials: Q
authors.lastname: Luo
authors.forename: Qingzhong
authors.initials: Q
authors.lastname: Liu
authors.forename: Yindi
authors.initials: Y
authors.lastname: Zhou
authors.forename: Lili
authors.initials: L
authors.lastname: Liu
authors.forename: Li
authors.initials: L
authors.lastname: Yu
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.forename: Jilong
authors.initials: J
authors.lastname: Shen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002395:Catecholamines / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010957:Plasmids; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012549:Schistosoma japonicum / Q000201:enzymology* / Q000235:genetics; D012550:Schistosoma mansoni / Q000201:enzymology / Q000235:genetics; D012554:Schistosomiasis japonica / Q000378:metabolism / Q000469:parasitology*; D013379:Substrate Specificity; D014169:Transformation, Bacterial; D014316:Tritium / Q000032:analysis; D014443:Tyrosine / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D002395:Catecholamines; D018076:DNA, Complementary; D015801:Helminth Proteins; D011993:Recombinant Fusion Proteins; D014316:Tritium; D014443:Tyrosine; D014446:Tyrosine 3-Monooxygenase