Characterization of the DMAE-modified juvenile excretory–secretory protein Juv-p120 of Litomosoides sigmodontis

Juv-p120 is an excretory–secretory 160 kDa glycoprotein of juvenile female Litomosoides sigmodontis and exhibits features typical for mucins. 50% of its molecular mass is attributed to posttranslational modifications with the unusual substituent dimethylaminoethanol (DMAE). By that Juv-p120 corresponds to the surface proteins of the microfilarial sheath, Shp3 and Shp3a. The secreted protein consists of 697 amino acids, organized in two different domains of repeat elements separated by a stretch of polar residues. The N-terminal domain shows fourteen P/S/T/F-rich repeat elements highly modified with phospho-DMAE substituted O-glycans confering a negative charge to the protein. The C-terminal domain is extremely rich in glutamine (35%) and leucine (25%) in less organized repeats and may play a role in oligomerization of Juv-p120 monomers. A protein family with a similar Q/L-rich region and conserved core promoter region was identified in Brugia malayi by homology screening and in Wuchereria bancrofti and Loa loa by database similarity search. One of the Q/L-rich proteins in each genus has an extended S/T-rich region and due to this feature is supposed to be a putative Juv-p120 ortholog. The corresponding modification of Juv-p120 and the microfilarial sheath surface antigens Shp3/3a explains the appearance of anti-sheath antibodies before the release of microfilariae. The function of Juv-p120 is unknown.

Graphical abstract. We molecularly characterized Juv-p120, an excretory–secretory glycoprotein of juvenile female Litomosoides sigmodontis. It is highly modified with phospho-dimethylaminoethanol (DMAE) responsible for serological cross-reaction to the microfilarial sheath surface proteins.Figure optionsDownload full-size imageDownload high-quality image (145 K)Download as PowerPoint slideResearch highlights► Juv-p120 is a 160 kDa ES-protein of juvenile female Litomosoides sigmodontis. ► 50% of the Juv-p120 molecular mass are P-DMAE substituted O-glycans. ► Juv-p120 is bifunctional organized: S/T-rich N- and Q/L-rich C-terminal repeats. ► Juv-p120 and the sheath surface proteins cross-react by their modifications ► Juv-p120 orthologs were identified in Brugia, Loa and Wuchereria.