Structure of the sulfated alpha-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.
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 alpha-L-fucans as inducers of acrosome reaction in conspecific and heterospecific sperm. Although all these fucans are linear polymers composed of 3-linked alpha-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-O- and 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.
Vilela-Silva
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AC
Laboratório de Tecido Conjuntivo, Hospital Universitário and Departamento de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Caixa Postal 68041, Rio de Janeiro, RJ, 21941-590, Brazil.
Alves
A P
AP
Valente
A P
AP
Vacquier
V D
VD
Mourão
P A
PA
D020101:Acrosome Reaction / Q000502:physiology*; D000818:Animals; D002240:Carbohydrate Sequence; D005260:Female; D005643:Fucose; D008297:Male; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010063:Ovum / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*; D012617:Sea Urchins; D013463:Sulfuric Acid Esters / Q000737:chemistry*
D011134:Polysaccharides; D013463:Sulfuric Acid Esters; D005643:Fucose; C007789:fucoidan