A zinc finger gene from Onchocerca volvulus encodes a protein with a functional signal peptide and an unusual Ser-His finger motif.
The filarial parasite Onchocerca volvulus is the causative agent of river blindness. In order to identify genes potentially involved in parasite development we cloned a zinc finger-encoding gene from this species. The ovzf-1 gene represents one member of a family of related zinc finger genes. The predicted ovzf-1 translation product of 447 amino acids includes a hydrophobic signal peptide, which is followed by 13 contiguous finger motifs. The domains of fingers II-XIII display several conserved amino acids and a typical Krüppel-like Cys2-His2 motif. The first finger domain has the two conserved Cys residues replaced with Ser residues; however, it includes all additional amino acids typical of zinc finger domains. The N-terminal domain functions as a signal peptide, as it directs secretion of a reporter protein and a truncated Ovzf protein. Expression of an Ovzf protein via the secretory pathway was also confirmed by demonstrating attachment of N-linked carbohydrates to the recombinant protein. Although the recombinant Ovzf protein also includes a signal peptide, immunofluorescence analyses localize it inside a specific compartment of the infected insect cell. Expression of ovzf mRNA is developmentally regulated; no specific transcript is detected in adult female worms but in the infective L3. Identification of a secreted protein that might function in modulating gene expression of host cells provides an interesting tool for the study of parasite-host interaction on a biochemical and molecular level.
Holst
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Department of Molecular Biology, Bernhard Nocht Institute for Tropical Medicine, Bernhard Nocht Strasse 74, 20359 Hamburg, Germany.
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D000595:Amino Acid Sequence; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary; D005260:Female; D005455:Fluorescent Antibody Technique; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006639:Histidine / Q000737:chemistry*; D008969:Molecular Sequence Data; D017181:Onchocerca volvulus / Q000235:genetics*; D021382:Protein Sorting Signals / Q000737:chemistry* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000737:chemistry*; D018411:Spodoptera; D013347:Subcellular Fractions / Q000378:metabolism; D016335:Zinc Fingers / Q000235:genetics*
D018076:DNA, Complementary; D015801:Helminth Proteins; D021382:Protein Sorting Signals; D012333:RNA, Messenger; C100611:ZF-1 protein, Onchocerca volvulus; D012694:Serine; D006639:Histidine