期刊
INFECTION AND IMMUNITY
卷 75, 期 1, 页码 184-192出版社
AMER SOC MICROBIOLOGY
DOI: 10.1128/IAI.00944-06
关键词
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资金
- NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES [T32AI007329, T32AI007389, R01AI046985] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF DENTAL &CRANIOFACIAL RESEARCH [R01DE015844] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES [K01DK062816, P30DK034928] Funding Source: NIH RePORTER
- NIAID NIH HHS [R01 AI05786, R01 AI046985, T32 AI007329, T32 AI07389, R01 AI46985, T32 AI007389] Funding Source: Medline
- NIDCR NIH HHS [R01 DE015844] Funding Source: Medline
- NIDDK NIH HHS [P30 DK34928-18, P30 DK034928, K01 DK062816] Funding Source: Medline
The apicomplexan parasite Cryptosporidium causes diarrheal disease worldwide. Proteolytic processing of proteins plays a significant role in host cell invasion by apicomplexan parasites. In previous studies, we described gp40/15, a Cryptosporidium sp. glycoprotein that is proteolytically cleaved to yield two surface glycopeptides (gp40 and gp15), which are implicated in mediating infection of host cells. In the present study, we showed that biosynthetically labeled gp40/15 is processed in Cryptosporidium parvum-infected HCT-8 cells. We identified a putative furin cleavage site RSRR down arrow in the deduced amino acid sequence of gp40/15 from C. parvum and from all Cryptosporidium hominis subtypes except subtype le. Both human furin and a protease activity present in a C. parvum lysate cleaved recombinant C. parvum gp40/15 protein into 2 peptides, identified as gp40 and gp15 by size and by immunoreactivity with specific antibodies. C. hominis gp40/15 subtype le, in which the RSRR sequence is replaced by ISKR, has an alternative furin cleavage site (KSISKR down arrow) and was also cleaved by both furin and the C. parvum lysate. Site-directed mutagenesis of the C. parvum RSRR sequence to ASRR resulted in inhibition of cleavage by furin and the C. parvum lysate. Cleavage of recombinant gp40/15 and a synthetic furin substrate by the C. parvum lysate was inhibited by serine protease inhibitors, by the specific furin inhibitor decanoyl-Arg-Val-Lys-Arg-chloromethylketone (Dec-RVKR-cmk), and by calcium chelators, suggesting that the parasite expresses a Ca2+ dependent, furin-like protease activity. The furin inhibitor Dec-RVKR-cmk decreased C. parvum infection of HCT-8 cells, suggesting that a furin-like protease activity may be involved in mediating host-parasite interactions.
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