Sm25, a major schistosome tegumental glycoprotein, is dependent on palmitic acid for membrane attachment.

Abstract

Sm25, a major antigen in the surface tegument of the parasitic helminth Schistosoma mansoni, is a 25 kDa N‐glycosylated glycoprotein which co‐purifies with isolated surface membranes and behaves as an integral membrane protein in Triton X‐114 (TX‐114). The deduced amino acid sequence of Sm25 shows a short C‐terminal hydrophobic domain between residues 163 and 180, containing six uncharged polar amino acids and followed by a Lys181‐Ser192 dipeptide. We were interested in whether or not this marginal C‐terminal amphiphilic domain is responsible for the association of Sm25 with the membrane or whether a post‐translational modification such as the addition of glycosyl phosphatidyl inositol (GPI) represents the membrane anchor for this molecule. We find that treatment with phosphatidyl inositol‐specific phospholipase C, which cleaves many GPI anchors, does not reveal Cross Reacting Determinant (CRD) on Sm25, nor affect the association of this protein with membranes, providing no support for the addition of GPI. However, Sm25 is palmitoylated via a thioester bond to the single Cys residue, at position 168, which lies within the C‐terminal hydrophobic domain. Removal of palmitate by reduction results in a marked decrease in the hydrophobicity of Sm25, as demonstrated by its partitioning into the aqueous rather than detergent phase of TX‐114 and its quantitative release from membrane preparations. The hydrophobicity of several membrane proteins in addition to Sm25 is also decreased by reduction, raising the possibility that fatty acylation by thioester linkage is an important mechanism used by schistosomes to stabilize protein‐membrane interactions.

Vaccination with Enzymatically Cleaved GPI-Anchored Proteins fromSchistosoma mansoniInduces Protection against Challenge Infection

“…However, the work by Teixeira de Melo et al [19] is different from our study since we are using here only GPI-anchored proteins and not the entire tegument. Several tegument and tegument-associated proteins have been evaluated as vaccine candidates in the last years, such as Sm29 [9], TSP2 [8], Sm22.6 [23], a Stomatin-Like Protein-2 [24], Sm-p80 (a subunit of calpain) [25], ECL (Sm200) [26], Sm25 [27, 28] among many others (for a better review see Pinheiro et al 2011 [29]). Even with many attempts using tegument proteins as subunit vaccines in the form of recombinant proteins or as DNA vaccines, up to now, no single vaccine candidate achieved the protection levels obtained by radiation attenuated cercariae [30].…”

Evaluation of Echinococcus multilocularis tetraspanins as vaccine candidates against primary alveolar echinococcosis

“…The conserved, crucial parts of these proteins-LEL domain (aa 1～aa 81 in figure 1) were compared with other known tetraspanins from helminthes using the Clustal W2 on-line service. Then we used the MegAlign component of DNAStar programme (Version 4.01 DNASTAR, Madison, Wis.) to construct a phylogenetic tree of transmembrane proteins, including the TSP1 to TSP7 tetraspanins of E. multilocularis; the Sm23 [20], Sm25 [23], Sm-TSP1 and Sm-TSP2 proteins of S. mansoni [19]; the Sj23 [21,22] and Sj25 proteins of S. japonicum [24], the Sh23 protein of S.…”

A comparative evaluation of poly-l-lysine-palmitic acid and Lipofectamine ™ 2000 for plasmid delivery to bone marrow stromal cells

“…PA is utilized by cells to control the intracellular trafficking of proteins [20,21]. It is also known to participate in receptor binding [22], endosomal uptake and release of proteins [23], cytoskeletal interactions [24], protein folding [25], cell growth [26], and protein-membrane interactions [27]. We hypothesized that PLL-PA conjugate will enhance the gene delivery due to its hydrophobicity, and improve the transport of pDNA/ polymer complexes across the plasma membrane [28].…”