Characterization of an intracellular cystatin homolog from the tick Haemaphysalis longicornis.
Cystatins are tight-binding inhibitors of papain-like cysteine proteases. On the basis of amino acid sequencing, cystatins can be subdivided into three closely related families, family 1, family 2 and family 3. Among them, only family 1 cystatins are intracellular. In this report, a gene encoding family 1 cystatin from tick Haemaphysalis longicornis (Hlcyst-1) has been identified. Its full-length cDNA is 437 bp, including an intact ORF encoding an expected protein with 98 amino acids. Sequence analysis demonstrated that it has significant homology with the known family 1 cystatin. The recombinant protein was expressed in a GST-fused soluble form in Escherichia coli, and its inhibitory activity against papain, cathepsin L, and cathepsin B was identified by fluorogenic substrate analysis. This is the first report of an intracellular cystatin homolog from the tick H. longicornis.
Zhou
Jinlin
J
Department of Frontier Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima 890-0065, Japan.
Liao
Min
M
Ueda
Mami
M
Gong
Haiyan
H
Xuan
Xuenan
X
Fujisaki
Kozo
K
D000595:Amino Acid Sequence; D000818:Animals; D015891:Cystatins / Q000737:chemistry* / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D008969:Molecular Sequence Data; D013987:Ticks / Q000235:genetics / Q000378:metabolism*
D015891:Cystatins