Cloning and Expression Analysis of Two Mucin-like Genes Encoding Microfilarial Sheath Surface Proteins of the Parasitic Nematodes Brugia and Litomosoides

• Published in: The Journal of biological chemistry 2002-12, Vol.277 (49), p.47603-47612
• Main Authors: Hirzmann, Jörg, Hintz, Martin, Kasper, Martin, Shresta, Tilak R., Taubert, Anja, Conraths, Franz J., Geyer, Rudolf, Stirm, Stephan, Zahner, Horst, Hobom, Gerd
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Animals; Base Sequence; Blotting, Northern; Blotting, Southern; Brugia malayi - metabolism; Brugia pahangi - metabolism; Carbohydrates - chemistry; Chromatography, Gas; Cloning, Molecular; DNA, Complementary - metabolism; Female; Filarioidea - metabolism; Male; Models, Genetic; Molecular Sequence Data; Monosaccharides - chemistry; Mucins - chemistry; Mucins - genetics; Mucins - metabolism; Promoter Regions, Genetic; Protein Structure, Tertiary; Rats; Reverse Transcriptase Polymerase Chain Reaction; RNA - metabolism; Sequence Homology, Amino Acid; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Transcription, Genetic
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M205770200

In several filarial genera the first stage larvae (microfilariae) are enclosed by an eggshell-derived sheath that provides a major interface between the parasite and the host immune system. Analysis of the polypeptide constituents of the microfilarial sheath from the cotton rat filaria Litomosoides sigmodontisidentified two abundant surface glycoproteins: Shp3a and Shp3. The corresponding genes and the orthologues of the human parasiteBrugia malayi and the rodent filaria Brugia pahangi were cloned and sequenced. They encode secreted, mucin-like proteins with N-terminal Ser/Thr-rich repeats and a C-terminal anchor domain rich in aromatic amino acids. About 75% of the protein molecular masses result from post-translational modifications. The Ser/Thr-rich motifs are supposed to serve as targets for dimethylaminoethanol-phosphate substitutions. These modifications were detected only on the sheaths of the late developmental stage of stretched microfilariae, corresponding with the expression of the proteins in the epithelium of the distal part of the uterus and the specific transcription of shp3 andshp3a in the anterior female worm segment. Genomic analysis of all three species demonstrated a conserved linkage of the two genes. Their transcripts undergo cis- andtrans-splicing. The transcription start sites of the primary transcripts were determined for the L. sigmodontisgenes. The core promoter regions are remarkably conserved between the paralogue genes Ls-shp3a andLs-shp3 and their orthologues inBrugia, implicating conserved regulatory elements.