Characterization of the Src/Abl hybrid kinase SmTK6 of Schistosoma mansoni.
Cellular protein-tyrosine kinases play key roles in signal transduction processes in eukaryotes. SmTK4 was the first Syk kinase identified in a parasite and found to be tissue-specifically transcribed in the gonads of adult Schistosoma mansoni. Functional analyses confirmed its role in oogenesis and spermatogenesis. As an SmTK4 upstream binding partner, the cellular protein-tyrosine kinase SmTK6 was isolated from a yeast two-hybrid library. Phylogenetic analyses performed in this study confirmed the first suggestions of a hybrid character of SmTK6. Biochemical studies made in Xenopus oocytes using inhibitors against Src (herbimycin A) and Abl (imatinib) kinases exhibited a biochemical inhibition profile of SmTK6, which was intermediate of Src and Abl kinases. As SmTK6 upstream interaction partners, we identified among others the known Src kinase SmTK3 and the Venus kinase receptor SmVKR1 of S. mansoni by yeast two-hybrid analyses, all of which co-localized in the gonads. Co-immunoprecipitation experiments confirmed interactions between SmTK6 and SmTK3 or SmVKR1. In Xenopus oocytes, it was finally shown that SmVKR1 but also SmTK3 were able to activate SmTK6 enzymatic activity indicating its functions in a receptor tyrosine kinase signal transduction cascade. These results not only demonstrate an intermediate but Src-biased profile of the unusual kinase SmTK6. They also strongly substantiate previous indications for a kinase complex, consisting of a receptor tyrosine kinase, Syk and Src kinases, which has been hypothesized to be involved in proliferation and differentiation processes in the gonads of schistosomes.
Institute for Parasitology, Justus-Liebig-University Giessen, 35392 Giessen, Germany.
Svenja
S
Beckmann
Institute for Parasitology, Justus-Liebig-University Giessen, 35392 Giessen, Germany.
Steffen
S
Hahnel
EA 4479, IFR 147, Universite Lille 1 Sciences et Technologies, 59655 Villeneuve d'Ascq Cedex, France.
Katia
K
Cailliau
Center for Infection and Immunity of Lille, Inserm U1019, CNRS-UMR 8204, Institut Pasteur Lille, 59019 Lille, France.
Mathieu
M
Vanderstraete
EA 4479, IFR 147, Universite Lille 1 Sciences et Technologies, 59655 Villeneuve d'Ascq Cedex, France.
Edith
E
Browaeys
Center for Infection and Immunity of Lille, Inserm U1019, CNRS-UMR 8204, Institut Pasteur Lille, 59019 Lille, France.
Colette
C
Dissous
Institute for Parasitology, Justus-Liebig-University Giessen, 35392 Giessen, Germany. Electronic address: Christoph.Grevelding@vetmed.uni-giessen.de.
Christoph G
CG
Grevelding
D000818:Animals; D001549:Benzamides; D016227:Benzoquinones / Q000494:pharmacology; D000081247:CSK Tyrosine-Protein Kinase; D002454:Cell Differentiation; D049109:Cell Proliferation; D006801:Humans; D000068877:Imatinib Mesylate; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D010802:Phylogeny; D010879:Piperazines / Q000494:pharmacology; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000378:metabolism*; D016315:Proto-Oncogene Proteins c-abl / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives; D012550:Schistosoma mansoni / Q000378:metabolism*; D012908:Snails; D020798:Two-Hybrid System Techniques; D014981:Xenopus; D019061:src-Family Kinases / Q000378:metabolism*
D001549:Benzamides; D016227:Benzoquinones; D047029:Lactams, Macrocyclic; D010879:Piperazines; D011743:Pyrimidines; D017828:Rifabutin; C020754:herbimycin; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D016315:Proto-Oncogene Proteins c-abl; D019061:src-Family Kinases; C000631346:CSK protein, human