title: RmKK, a tissue kallikrein inhibitor from Rhipicephalus microplus eggs.
abstract: Rhipicephalus microplus is an important ectoparasite that is responsible for transmission of anaplasmosis and babesiosis to cattle. Tissue kallikrein inhibitors might play an important role in R. microplus eggs. In the present work, we purified and characterized, a tissue kallikrein inhibitor presents in R. microplus eggs (RmKK), a protein which contains two Kunitz domain in tandem. Purified inhibitor was confirmed by amino terminal determination and its dissociation constant (Ki) for bovine trypsin and porcine pancreatic kallikrein were 0.6 nM and 91.5 nM, respectively. Using a cDNA library from R. microplus midgut, we cloned the cDNA fragment encoding mature RmKK and expressed the protein in Pichia pastoris system. Recombinant RmKK was purified by ion exchange chromatography and presented molecular mass of 16.3 kDa by MALDI-TOF analysis. Moreover, RmKK showed a tight binding inhibition for serine proteases as bovine trypsin (Ki=0.2 nM) and porcine pancreatic kallikrein (PPK) (Ki=300 nM). We performed, for the first time, the characterization of a tissue kallikrein inhibitor presents in R. microplus eggs, which the transcript is produced in the adult female gut. BmKK seems to be the strongest PPK inhibitor among all BmTIs present in the eggs and larvae (Andreotti et al., 2001; Sasaki et al., 2004). This data suggests that BmKK may participate in the development of tick egg and larvae phase.
authors.affiliation: Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Patrícia A
authors.initials: PA
authors.lastname: Abreu
authors.affiliation: Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Tatiane S
authors.initials: TS
authors.lastname: Soares
authors.affiliation: Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Diego S
authors.initials: DS
authors.lastname: Buarque
authors.affiliation: Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Ricardo S
authors.initials: RS
authors.lastname: Torquato
authors.affiliation: Department of Biochemistry, Universidade Federal de São Paulo, São Paulo, SP, Brazil. Electronic address: tanaka.bioq@epm.br.
authors.forename: Aparecida S
authors.initials: AS
authors.lastname: Tanaka
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D060829:Arthropod Proteins / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D004789:Enzyme Activation; D005260:Female; D008969:Molecular Sequence Data; D010063:Ovum / Q000378:metabolism*; D011485:Protein Binding; D048494:Rhipicephalus / Q000145:classification* / Q000378:metabolism*; D013045:Species Specificity; D014018:Tissue Distribution; D020840:Tissue Kallikreins / Q000037:antagonists & inhibitors*
chemical_list: D060829:Arthropod Proteins; D020840:Tissue Kallikreins
keywords: Eggs; Rhipicephalus microplus; Serine protease inhibitor; Tissue kallikrein inhibitor