A family of cathepsin F cysteine proteases of Clonorchis sinensis is the major secreted proteins that are expressed in the intestine of the parasite.
Cysteine proteases of helminth parasites play essential roles in parasite physiology as well as in a variety of important pathobiological processes. In this study, we identified a multigene family of cathepsin F cysteine proteases in Clonorchis sinensis (CsCFs). We identified a total of 12 CsCF genes through cDNA cloning using degenerate PCR primers followed by RACE. Sequence and phylogenetic analysis of the genes suggested they belonged to the cathepsin F-like enzyme family and further clustered into three different subfamilies. Enzymatic and proteomic analysis of C. sinensis excretory and secretory products (ESP) revealed that multiple isoforms of CsCF were the major proteins present in the ESP and the proteolytic activity of the ESP is mainly attributable to the enzymes. Comparative analysis of representative enzymes for each subfamily, CsCF-4, CsCF-6, and CsCF-11, showed that they share similar biochemical properties typical for cathepsin F-like enzymes, but significant differences were also identified. The enzymes were expressed throughout various developmental stages of the parasite and the transcripts increased gradually in accordance with the maturation of the parasite. Immunolocalization analysis of CsCFs showed that they were mainly localized in the intestine and intestinal contents of the parasite. These results collectively suggested that CsCFs, which are apparently synthesized in the epithelial cells lining the parasite intestine and secreted into the intestinal lumen of the parasite, might have a cooperative role for nutrient uptake in the parasite. Furthermore, they were eventually secreted into outside of the parasite and may perform additional functions for host-parasite interactions.
Kang
Jung-Mi
JM
Department of Parasitology, Brain Korea 21 Biomedical Center, and Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju 660-751, Republic of Korea.
Bahk
Young-Yil
YY
Cho
Pyo-Yun
PY
Hong
Sung-Jong
SJ
Kim
Tong-Soo
TS
Sohn
Woon-Mok
WM
Na
Byoung-Kuk
BK
D000595:Amino Acid Sequence; D000818:Animals; D056646:Cathepsin F / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D003004:Clonorchis sinensis / Q000737:chemistry / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D005110:Extracellular Space / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D015870:Gene Expression; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000201:enzymology*; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D021381:Protein Transport; D016415:Sequence Alignment
D015801:Helminth Proteins; D056646:Cathepsin F