The tissue factor pathway inhibitor 1 of Sciaenops ocellatus possesses antimicrobial activity and is involved in the immune response against bacterial infection.
Tissue factor pathway inhibitor 1 (TFPI-1) is a Kunitz-type serine protease inhibitor that regulates the activation of tissue factor-induced coagulation. In teleosts, TFPI-1-like sequences have been found to exist in two species (Danio rerio and Cyprinus carpio); however, the potential function of fish TFPI-1 has not been investigated. In this study, we identified and analyzed a TFPI-1 homologue, SoTFPI-1, from red drum (Sciaenops ocellatus). The deduced amino acid sequence of SoTFPI-1 is 284 residues in length and contains three Kunitz domains, an acidic N-terminus, and a basic C-terminus. SoTFPI-1 shares 49.5% and 46.9% overall sequence identities with the TFPI-1 of D. rerio and C. carpio, respectively. Quantitative real time RT-PCR analysis showed that constitutive SoTFPI-1 expression occurred, in increasing order, in kidney, brain, liver, gill, blood, spleen, muscle, and heart. Bacterial infection and lipopolysaccharide exposure upregulated SoTFPI-1 expression in kidney in time-dependent manners. Recombinant SoTFPI-1 (rSoTFPI-1) purified from Escherichia coli exhibits not only serine protease inhibitor activity but also bactericidal activity in a manner that is independent of any host factors. A synthetic peptide, TO17, corresponding to the C-terminal basic region of SoTFPI-1 also possesses antibacterial effect that is more potent than that of the full-length rSoTFPI-1. Taken together, these results demonstrate that (i) SoTFPI-1 is a biologically active serine protease inhibitor endowed with bactericidal property; (ii) provide the first indication that teleost TFPI-1 is likely to be involved in anti-microbial infection and thus is linked to innate immune defense.
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 nanhai Road, Qingdao 266071, PR China.
Min
M
Zhang
Li
L
Sun
D000595:Amino Acid Sequence; D000818:Animals; D001424:Bacterial Infections / Q000201:enzymology / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D004797:Enzyme-Linked Immunosorbent Assay; D008074:Lipoproteins / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D008074:Lipoproteins; C051928:lipoprotein-associated coagulation inhibitor