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Profiling of proteolytic enzymes in the gut of the tick Ixodes ricinus reveals an evolutionarily conserved network of aspartic and cysteine peptidases.

Sojka D, Franta Z, Horn M, Hajdusek O, Caffrey CR, Mares M, Kopácek P - Parasit Vectors (2008)

Bottom Line: Overall, our results demonstrate the presence of a network of cysteine and aspartic peptidases that conceivably operates to digest host blood proteins in a concerted manner.Significantly, the peptidase components of this digestive network are orthologous to those described in other parasites, including nematodes and flatworms.Accordingly, the present data and those available for other tick species support the notion of an evolutionary conservation of a cysteine/aspartic peptidase system for digestion that includes ticks, but differs from that of insects relying on serine peptidases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Parasitology, Biology Centre, Academy of Sciences of the Czech Republic, Ceské Budejovice, CZ-370 05, The Czech Republic. dsojka@seznam.cz.

ABSTRACT

Background: Ticks are vectors for a variety of viral, bacterial and parasitic diseases in human and domestic animals. To survive and reproduce ticks feed on host blood, yet our understanding of the intestinal proteolytic machinery used to derive absorbable nutrients from the blood meal is poor. Intestinal digestive processes are limiting factors for pathogen transmission since the tick gut presents the primary site of infection. Moreover, digestive enzymes may find practical application as anti-tick vaccine targets.

Results: Using the hard tick, Ixodes ricinus, we performed a functional activity scan of the peptidase complement in gut tissue extracts that demonstrated the presence of five types of peptidases of the cysteine and aspartic classes. We followed up with genetic screens of gut-derived cDNA to identify and clone genes encoding the cysteine peptidases cathepsins B, L and C, an asparaginyl endopeptidase (legumain), and the aspartic peptidase, cathepsin D. By RT-PCR, expression of asparaginyl endopeptidase and cathepsins B and D was restricted to gut tissue and to those developmental stages feeding on blood.

Conclusion: Overall, our results demonstrate the presence of a network of cysteine and aspartic peptidases that conceivably operates to digest host blood proteins in a concerted manner. Significantly, the peptidase components of this digestive network are orthologous to those described in other parasites, including nematodes and flatworms. Accordingly, the present data and those available for other tick species support the notion of an evolutionary conservation of a cysteine/aspartic peptidase system for digestion that includes ticks, but differs from that of insects relying on serine peptidases.

No MeSH data available.


Related in: MedlinePlus

Nucleotide and deduced amino acid sequence of Ixodes ricinus cathepsin C (IrCC). The depictions of PCR primers, putative 20 AA signal peptide, four potential N-glycosylation sites and active site residues C256, H409, Q250 and N431 are as in Fig 4.
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Figure 6: Nucleotide and deduced amino acid sequence of Ixodes ricinus cathepsin C (IrCC). The depictions of PCR primers, putative 20 AA signal peptide, four potential N-glycosylation sites and active site residues C256, H409, Q250 and N431 are as in Fig 4.

Mentions: Cathepsin C belongs to the clan CA papain family, but unlike B and L it acts solely as an exopeptidase. It has been shown to sequentially remove dipeptides from the substrate N-terminus (therefore alternatively named as dipeptidyl peptidase I). The cDNA sequence of IrCC [GenBank: EU128750] is 1597 bp long and encodes an enzyme precursor of 465 AA residues (Fig. 6). Calculated molecular weight of the proenzyme without signal peptide is 49.812 Da and the theoretical isoelectric point is 6.88. Based on the structure of human cathepsin C, the active site residues are Q250, C256, H409 and N431. The predicted signal peptide counts for 20 AA residues and the proenzyme has four potential N-glycosylation sites, one close to the predicted mature N-terminus.


Profiling of proteolytic enzymes in the gut of the tick Ixodes ricinus reveals an evolutionarily conserved network of aspartic and cysteine peptidases.

Sojka D, Franta Z, Horn M, Hajdusek O, Caffrey CR, Mares M, Kopácek P - Parasit Vectors (2008)

Nucleotide and deduced amino acid sequence of Ixodes ricinus cathepsin C (IrCC). The depictions of PCR primers, putative 20 AA signal peptide, four potential N-glycosylation sites and active site residues C256, H409, Q250 and N431 are as in Fig 4.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2289814&req=5

Figure 6: Nucleotide and deduced amino acid sequence of Ixodes ricinus cathepsin C (IrCC). The depictions of PCR primers, putative 20 AA signal peptide, four potential N-glycosylation sites and active site residues C256, H409, Q250 and N431 are as in Fig 4.
Mentions: Cathepsin C belongs to the clan CA papain family, but unlike B and L it acts solely as an exopeptidase. It has been shown to sequentially remove dipeptides from the substrate N-terminus (therefore alternatively named as dipeptidyl peptidase I). The cDNA sequence of IrCC [GenBank: EU128750] is 1597 bp long and encodes an enzyme precursor of 465 AA residues (Fig. 6). Calculated molecular weight of the proenzyme without signal peptide is 49.812 Da and the theoretical isoelectric point is 6.88. Based on the structure of human cathepsin C, the active site residues are Q250, C256, H409 and N431. The predicted signal peptide counts for 20 AA residues and the proenzyme has four potential N-glycosylation sites, one close to the predicted mature N-terminus.

Bottom Line: Overall, our results demonstrate the presence of a network of cysteine and aspartic peptidases that conceivably operates to digest host blood proteins in a concerted manner.Significantly, the peptidase components of this digestive network are orthologous to those described in other parasites, including nematodes and flatworms.Accordingly, the present data and those available for other tick species support the notion of an evolutionary conservation of a cysteine/aspartic peptidase system for digestion that includes ticks, but differs from that of insects relying on serine peptidases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Parasitology, Biology Centre, Academy of Sciences of the Czech Republic, Ceské Budejovice, CZ-370 05, The Czech Republic. dsojka@seznam.cz.

ABSTRACT

Background: Ticks are vectors for a variety of viral, bacterial and parasitic diseases in human and domestic animals. To survive and reproduce ticks feed on host blood, yet our understanding of the intestinal proteolytic machinery used to derive absorbable nutrients from the blood meal is poor. Intestinal digestive processes are limiting factors for pathogen transmission since the tick gut presents the primary site of infection. Moreover, digestive enzymes may find practical application as anti-tick vaccine targets.

Results: Using the hard tick, Ixodes ricinus, we performed a functional activity scan of the peptidase complement in gut tissue extracts that demonstrated the presence of five types of peptidases of the cysteine and aspartic classes. We followed up with genetic screens of gut-derived cDNA to identify and clone genes encoding the cysteine peptidases cathepsins B, L and C, an asparaginyl endopeptidase (legumain), and the aspartic peptidase, cathepsin D. By RT-PCR, expression of asparaginyl endopeptidase and cathepsins B and D was restricted to gut tissue and to those developmental stages feeding on blood.

Conclusion: Overall, our results demonstrate the presence of a network of cysteine and aspartic peptidases that conceivably operates to digest host blood proteins in a concerted manner. Significantly, the peptidase components of this digestive network are orthologous to those described in other parasites, including nematodes and flatworms. Accordingly, the present data and those available for other tick species support the notion of an evolutionary conservation of a cysteine/aspartic peptidase system for digestion that includes ticks, but differs from that of insects relying on serine peptidases.

No MeSH data available.


Related in: MedlinePlus