Two secreted cystatins of the soft tick Ornithodoros moubata: differential expression pattern and inhibitory specificity.
Two genes coding for cysteine peptidase inhibitors of the cystatin family (Om-cystatin 1 and 2) were isolated from a gut-specific cDNA library of the soft tick Ornithodoros moubata. Both cystatins were clearly down-regulated after a blood meal. Om-cystatin 1 is mainly expressed in the tick gut, while Om-cystatin 2 mRNA was also found in other tick tissues. Authentic Om-cystatin 2 was significantly more abundant than Om-cystatin 1 in the gut contents of fasting ticks and was associated with hemosome-derived residual bodies accumulated in the gut lumen. Om-cystatin 2 was also expressed by type 2 secretory cells in the salivary glands of unfed ticks. The inhibitory specificity of recombinant Om-cystatins 1 and 2 was tested with mammalian cysteine peptidases, as well as endogenous cysteine peptidases present in the tick gut. Both cystatins efficiently inhibited papain-like peptidases, including cathepsin B and H, but differed significantly in their affinity towards cathepsin C and failed to block asparaginyl endopeptidase. Our results suggest that the secreted cystatin isoinhibitors are involved in the regulation of multiple proteolytic targets in the tick digestive system and tick-host interaction.
Grunclová
Lenka
L
Faculty of Biological Sciences, University of South Bohemia, CZ-370 05 Ceské Budejovice, Czech Republic.
Horn
Martin
M
Vancová
Marie
M
Sojka
Daniel
D
Franta
Zdenek
Z
Mares
Michael
M
Kopácek
Petr
P
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D015891:Cystatins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D018076:DNA, Complementary; D019084:Fluorescent Antibody Technique, Indirect; D005786:Gene Expression Regulation; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013987:Ticks
D015891:Cystatins; D017931:DNA Primers; D018076:DNA, Complementary