Structure of the sulfated  -L-fucan from the egg jelly coat of the sea urchin Strongylocentrotus franciscanus: patterns of preferential 2-O- and 4-O-sulfation determine sperm cell recognition

Abstract

The egg jelly coats of sea urchins contains sulfated polysaccharides responsible for inducing the sperm acrosome reaction which is an obligatory event for sperm binding to, and fusion with, the egg. Here, we extend our study to the sea urchin Strongylocentrotus franciscanus. The egg jelly of this species contains a homofucan composed of 2-O-sulfated, 3-linked units which is the simplest structure ever reported for a sulfated fucan. This polysaccharide was compared with other sulfated α-L-fucans as inducers of acrosome reaction in conspecific and heterospecific sperm. Although all these fucans are linear polymers composed of 3-linked α-L-fucopyranosyl units, they differ in the proportions of 2-O-and 4-O-sulfation. The reactivity of the sperm of each species is more sensitive to the egg jelly sulfated fucan found in their own species. The reactivity of the sperm does not correlate with the charge density of the fucan, but with the proportion of 2-Oand 4-O-sulfation. The pattern of sulfation may be an important feature for recognition of fucans by the sperm receptor contributing to the species-specificity of fertilization.

Antithrombin-mediated Anticoagulant Activity of Sulfated Polysaccharides

“…The sea urchin Strongylocentrotus franciscanus contains a related polysaccharide composed of 2-sulfated, 1,3-linked ␣-L-fucose (Fig. 1D) (25). Finally, the following repeating structure (-4-␣-D-Gal-133-␤-D-Gal-13) was found in the red alga Botryocladia occidentalis.…”

Structure versus anticoagulant and antithrombotic actions of marine sulfated polysaccharides

“…The MSP with well-defi ned chemical structures (SF, SG and GAG in Figures 1 and 2) are extracted from echinoderms (Echinodermata) like sea cucumbers (Mulloy et al, 2004); (B) Lytechinus variegatus (Alves et al, 1997); (E) Strongylocentrotus purpuratus-I (Stimpson, 1857) (Alves et al, 1998) Vilela-Silva et al, 2002); and (H) Strongylocentrotus franciscanus (A. Agassiz, 1863) Vilela-Silva et al, 1999). (Castro et al, 2009) (Santos et al, 1992) (Mourão & Perlin, 1987); (E) both Botryocladia occidentalis (Kylin, 1931) and Gelidium crinale (Gaillon 1828) express [3-β-D-Galp-1→4-α-Gal-1→] n with different sulfation contents (Pereira et al, 2005;Fonseca et al, 2008); and (F) the DS from Styela plicata, Halocynthia pyriformis (Rathke, 1806), and Ascidian nigra (Savigny, 1816) are composed of [4-α-L-IdoA-1→3-β-D-GalNAc-1] n with also different sulfation patterns (Pavão et al, 1995;Pavão et al, 1998).…”

“…Among all the MSP with well-defined chemical structures described so far (Figures 1 and 2), there is a single description from the body wall of the sea cucumber ( Figure 1A) (Mulloy et al, 2004), a few examples of SG isolated from the tunic of ascidians ( Figure 2C and 2D) (Mourão & Perlin, 1987;Santos et al, 1992;Pavão et al, 1998), and some reports from specific red algal cell walls ( Figure 2E) (Pereira et al, 2005;Fonseca et al, 2008). All of the remaining structures ( Figure 1B -H and 2A and B) belong to the egg jelly coat of sea urchins (Alves et al, 1997;Alves et al, 1998;Vilela-Silva, et al, 1999;Vilela-Silva et al, 2002;Mulloy et al, 2004) The body of some species of ascidians also contains peculiar GAG that show sulfation patterns distinct from mammalian GAG (Pavão et al, 1995;Pavão et al, 1998), as exemplified by the tunicate dermatan sulfates (DS) in Figure 2F.…”

Modifications of Acrosome Reaction-Inducing Egg Coat Glycans

“…In sea urchins, the fucose sulfate polymer (FSP) in egg jelly is the major AR inducer (5). Structures of FSP in different sea urchin species have been described (6)(7)(8)(9). They are shown in Table 1 AR by binding to the receptor for egg jelly (REJ1), a 210-kDa glycoprotein on the sperm membrane (10).…”