A membrane-associated metalloprotease of Taenia solium metacestode structurally related to the FACE-1/Ste24p protease family.
The CaaX proteases are intimately involved in the post-translational modification of prenylated proteins and play a critical role in the activation/stabilization of membrane-bound or secreted molecules constituting the CAAX protein family. In this study, we have isolated a full-length cDNA putatively encoding a type I CaaX protease of the Taenia solium metacestode (TsM), which an agent causative of human neurocysticercosis. The cDNA, designated TsSte24p, comprised 1,505 bp and coded for an open reading frame of 472 amino acids with predicted Mr 54.5 kDa. This monoexonic TsSte24p gene existed as a single copy within the TsM genome and constantly expressed in the parasite from metacestode to adult stages. The TsSte24p exhibited the typical CaaX protease topology, including seven transmembrane domains and a metalloprotease segment with a zinc-binding motif. It shared a significant degree of sequence identity with the type I CaaX proteases such as Saccharomyces cerevisiae Ste24p and Caenorhabditis elegans CeFACE-1. A comparative phylogenetic analysis demonstrated that this protein family is tightly conserved across taxa, from bacteria to mammals. The bacterially expressed recombinant TsSte24p showed proteolytic activity, with an optimal pH of 7.5. The enzyme activity was significantly inhibited by EDTA. Its activity was increased in the presence of low concentrations of the Zn2+(0.001-0.01 mM); but was reversibly down-regulated at high doses (over 0.1 mM). The native TsSte24p appeared to function as a homodimer, the subunits of which were linked to each other via covalent disulfide bond. The protein was localized in the bladder wall and scolex with differential patterns of distribution. Our results indicated that TsSte24p is a zinc-dependent metalloprotease, which belongs to the FACE-1/Ste24p protease family.
Cai
Guo-Bin
GB
Department of Molecular Parasitology and Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, 300, Cheoncheon-dong Jangan-gu, Suwon, Gyeonggi-do 440-746, South Korea.
Bae
Young-An
YA
Kim
Seon-Hee
SH
Na
Byoung-Kuk
BK
Kim
Tong-Soo
TS
Jiang
Ming-Sen
MS
Kong
Yoon
Y
D000595:Amino Acid Sequence; D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D001483:Base Sequence; D015139:Blotting, Southern; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003551:Cysticercosis / Q000469:parasitology*; D005260:Female; D015723:Gene Library; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008666:Metalloendopeptidases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010802:Phylogeny; D017510:Protein Folding; D018510:RNA, Helminth / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D013047:Specific Pathogen-Free Organisms; D013499:Surface Properties; D041201:Taenia solium / Q000201:enzymology* / Q000235:genetics
D000909:Antibodies, Helminth; D029742:Caenorhabditis elegans Proteins; D008565:Membrane Proteins; D018510:RNA, Helminth; D029701:Saccharomyces cerevisiae Proteins; C473144:fce-1 protein, C elegans; D008666:Metalloendopeptidases; C491251:STE24 protein, S cerevisiae