title: Hemoglobinase activity of a cysteine protease from the ixodid tick Haemaphysalis longicornis.
abstract: We report here the molecular characterization and possible function of a cysteine protease (termed HlCPL-A) identified in the midgut of the hard tick Haemaphysalis longicornis. HlCPL-A is a 333 amino acid protein belonging to the papain family of the cysteine protease. A construct encoding proHlCPL-A was expressed in Escherichia coli and purified as both procathepsin L and active processed cathepsin L forms. The HlCPL-A gene expression was up-regulated by blood-feeding process. HlCPL-A exhibited substrate specificity against synthetic peptidyl substrates (Z-Phe-Arg-MCA and Z-Arg-Arg-MCA; k(cat)/K(m)=0.19 and 0.0023 M(-1) S(-1), respectively). The proteolytic activity of HlCPL-A was inhibited by leupeptin, antipain and E-64 but was unaffected by pepstatin. HlCPL-A was capable of degrading bovine hemoglobin at pH 3.2 to 5.6. These results suggest that HlCPL-A may play important roles in the digestion of host hemoglobin in ticks.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Kayoko
authors.initials: K
authors.lastname: Yamaji
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Tsuji
authors.forename: Takeharu
authors.initials: T
authors.lastname: Miyoshi
authors.forename: M Khyrul
authors.initials: MK
authors.lastname: Islam
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hatta
authors.forename: M Abdul
authors.initials: MA
authors.lastname: Alim
authors.lastname: Anisuzzaman
authors.forename: Akio
authors.initials: A
authors.lastname: Takenaka
authors.forename: Kozo
authors.initials: K
authors.lastname: Fujisaki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism*; D026863:Ixodidae / Q000145:classification / Q000201:enzymology*; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity
chemical_list: D006454:Hemoglobins; D011994:Recombinant Proteins; D003546:Cysteine Endopeptidases