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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

Phylogenetic relation of Ixodes ricinus gut-associated cysteine peptidases (clan CA, family C1) to selected representatives of the papain family. The tree was reconstructed by the Neighbor-joining method using amino acid sequences spanning across the homologous domains of mature enzymes. The horizontal bar represents a distance of 0.1 substitutions per site. Numbers at the branches display bootstrap support. Cathepsins B: Homo sapiens (AAH95408), Rattus norvegicus (P00787), Ixodes ricinus (ABO26563), Haemaphysalis longicornis (BAF43801), Schistosoma mansoni (P25792), Schistosoma japonicum (P43157); Cathepsins L: H. sapiens (M20496), R. norvegicus (AAH63175), I. ricinus (ABO26562), Boophilus microplus (AF227957), S. mansoni (CathL1 (Z32529), CathL2 (U07345)), S. japonicum (CathL1 (U38476), CathL2 (U38475)), Trypanosoma cruzii (P25779); Cathepsins C: H. sapiens (X87212), R. norvegicus (D90404), I. ricinus (ABV29335), S. mansoni (Z32531), S. japonicum (U77932).
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Figure 3: Phylogenetic relation of Ixodes ricinus gut-associated cysteine peptidases (clan CA, family C1) to selected representatives of the papain family. The tree was reconstructed by the Neighbor-joining method using amino acid sequences spanning across the homologous domains of mature enzymes. The horizontal bar represents a distance of 0.1 substitutions per site. Numbers at the branches display bootstrap support. Cathepsins B: Homo sapiens (AAH95408), Rattus norvegicus (P00787), Ixodes ricinus (ABO26563), Haemaphysalis longicornis (BAF43801), Schistosoma mansoni (P25792), Schistosoma japonicum (P43157); Cathepsins L: H. sapiens (M20496), R. norvegicus (AAH63175), I. ricinus (ABO26562), Boophilus microplus (AF227957), S. mansoni (CathL1 (Z32529), CathL2 (U07345)), S. japonicum (CathL1 (U38476), CathL2 (U38475)), Trypanosoma cruzii (P25779); Cathepsins C: H. sapiens (X87212), R. norvegicus (D90404), I. ricinus (ABV29335), S. mansoni (Z32531), S. japonicum (U77932).

Mentions: The three clan CA cysteine peptidases, namely IrCB, IrCL and IrCC could be clearly classified using multiple sequence alignments followed by a phylogenetic analysis (Fig. 3). The GenBank blast program blastp [19] search of the IrCD sequence revealed the closest relation (55% identity) as longepsin, the aspartic peptidase from H. longicornis [12].


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)

Phylogenetic relation of Ixodes ricinus gut-associated cysteine peptidases (clan CA, family C1) to selected representatives of the papain family. The tree was reconstructed by the Neighbor-joining method using amino acid sequences spanning across the homologous domains of mature enzymes. The horizontal bar represents a distance of 0.1 substitutions per site. Numbers at the branches display bootstrap support. Cathepsins B: Homo sapiens (AAH95408), Rattus norvegicus (P00787), Ixodes ricinus (ABO26563), Haemaphysalis longicornis (BAF43801), Schistosoma mansoni (P25792), Schistosoma japonicum (P43157); Cathepsins L: H. sapiens (M20496), R. norvegicus (AAH63175), I. ricinus (ABO26562), Boophilus microplus (AF227957), S. mansoni (CathL1 (Z32529), CathL2 (U07345)), S. japonicum (CathL1 (U38476), CathL2 (U38475)), Trypanosoma cruzii (P25779); Cathepsins C: H. sapiens (X87212), R. norvegicus (D90404), I. ricinus (ABV29335), S. mansoni (Z32531), S. japonicum (U77932).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Phylogenetic relation of Ixodes ricinus gut-associated cysteine peptidases (clan CA, family C1) to selected representatives of the papain family. The tree was reconstructed by the Neighbor-joining method using amino acid sequences spanning across the homologous domains of mature enzymes. The horizontal bar represents a distance of 0.1 substitutions per site. Numbers at the branches display bootstrap support. Cathepsins B: Homo sapiens (AAH95408), Rattus norvegicus (P00787), Ixodes ricinus (ABO26563), Haemaphysalis longicornis (BAF43801), Schistosoma mansoni (P25792), Schistosoma japonicum (P43157); Cathepsins L: H. sapiens (M20496), R. norvegicus (AAH63175), I. ricinus (ABO26562), Boophilus microplus (AF227957), S. mansoni (CathL1 (Z32529), CathL2 (U07345)), S. japonicum (CathL1 (U38476), CathL2 (U38475)), Trypanosoma cruzii (P25779); Cathepsins C: H. sapiens (X87212), R. norvegicus (D90404), I. ricinus (ABV29335), S. mansoni (Z32531), S. japonicum (U77932).
Mentions: The three clan CA cysteine peptidases, namely IrCB, IrCL and IrCC could be clearly classified using multiple sequence alignments followed by a phylogenetic analysis (Fig. 3). The GenBank blast program blastp [19] search of the IrCD sequence revealed the closest relation (55% identity) as longepsin, the aspartic peptidase from H. longicornis [12].

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