The phenoloxidase activity and antibacterial function of a tyrosinase from scallop Chlamys farreri.
Tyrosinase (TYR), also known as monophenol monooxygenase, is a ubiquitous binuclear copper-containing enzyme which catalyzes the hydroxylation of phenols to catechols and the oxidation of catechols to quinones. In the present study, the cDNA of a tyrosinase (CfTYR) was identified from scallop Chlamys farreri, which encoded a polypeptide of 486 amino acids. The CfTYR mRNA transcripts were expressed in all the tested tissues, including haemocytes, adductor muscle, kidney, hepatopancreas, gill, gonad and mantle, with the highest level in mantle. The expression level of CfTYR mRNA in haemocytes decreased significantly during 3-6 h after LPS stimulation, and reached the lowest level at 6 h (0.05-fold, P < 0.05). Then, it began to increase at 12 h (0.32-fold, P > 0.05), and reached the highest level at 24 h (2.91-fold, P < 0.05). At 3 h after LPS stimulation, the phenoloxidase activity catalyzing L-dopa and dopamine in haemolymph increased significantly to 53.13 and 40.36 U mg(-1) respectively, but it decreased to 10.82 U mg(-1) and even undetectable level after CfTYR activity was inhibited. Furthermore, the antibacterial activity of haemolymph against Escherichia coli was also increased significantly at 3 h after LPS stimulation, but it decreased significantly when the haemolymph was treated by TYR inhibitor. The recombinant protein of the mature CfTYR peptide expressed in the in vitro Glycoprotein Expression Kit displayed phenoloxidase activity of 64.36 ± 5.51 U mg(-1) in the present of trypsinase and Cu(2+). These results collectively suggested that CfTYR was a homologue of tyrosinase in scallop C. farreri with the copper-dependence phenoloxidase activity, and it could be induced after immune stimulation and mediate immune response for the elimination of invasive pathogens in scallop.
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
Zhi
Z
Zhou
Duojiao
D
Ni
Mengqiang
M
Wang
Lingling
L
Wang
Leilei
L
Wang
Xiaowei
X
Shi
Feng
F
Yue
Rui
R
Liu
Linsheng
L
Song
D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects* / Q000502:physiology; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006434:Hemocytes / Q000187:drug effects / Q000201:enzymology; D006458:Hemolymph / Q000201:enzymology / Q000382:microbiology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*; D049897:Pectinidae / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology*; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D000276:Adjuvants, Immunologic; D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D014442:Monophenol Monooxygenase