Structural Characterisation of Porcine Seminal Plasma Psp-I/Psp-li
249
were characterised. Except for a few monoantennary structures, all the oligosacchari des are di- or triantennary glycans sharing a (GlcNAc)z(ManhGlcNAc
(Fuc)GlcNAc core. Each antenna of diantennary structures displays combinations
of
[NeuAca2-61 0_1 [Gala1-310-1 [(Gal!GalNAC)~1-410_I[GlcNAc(Fuca1-3)0_1
~1-(2/4)10_1 Man sequence. A monosialylated oligosaccharide structure bearing
terminal NeuGly instead of NeuAc was also characterised. The third branch of
triantennary structures consist of (Gala1- 3 )0-1 Gal~ 1-4-GlcNAc sequences 131-4linked to the mannose residue or ~1-(3/6)-linked to the outer galactose residue of
the 1-3 antenna. Disialylated glycans display NeuAca2-6Gal~1-4GlcNAc or
NeuAca2-6GalNAc~ 1-4GlcNAc sequences.
Despite being PSP-I/PSP-II heterodimer the major protein of boar seminal
plasma, its function remains elusive. An interesting possibility is that the oligosaccharides participate in PSP-I/PSP-II function. Structural analysis of the oligosaccharides derived from glycodelin, a human glycoprotein with potent immunosuppressive and contraceptive activities, showed that the major non-reducing
epitopes in the complex-type glycans are Gal~1-4GlcNAc (lacNAc), GalNAc~1-4
GlcNAc (lacdiNAc), NeuAca2-6Gal~1-4-GlcNAc (sialylated lacNAc), NeuAc
a2-6GalNAc~1-4-GlcNAc (sialylated lacdiNAc), Gal~1-4(Fuca1-3)GlcNAc
(Lewis X ), and GalNAc~1-4(Fuca1-3)GlcNAc (lacdiNAc analogue ofLewis X ) (Dell
et al. 1995). The authors have put forward the hypothesis that the oligosaccharides bearing sialylated lacNAc or lacdiNAc antennae may manifest immunosuppressive effect by blocking adhesive and activation-related events mediated by
CD22, the human B cell associated receptor, and that oligo saccharides with fucosylated lacdiNAc antennae might block selectin -mediated adhesion [401. Boar
seminal plasma contains immunosuppressive activity associated with 14 kDa
protein(s) (Veselsky el al. 1996). Both, the molecular mass and the type of glycosylation of the PSP-I/PSP-II subunits would support immunosuppressive function
for PSP-I and PSP-II glycoforms. The structural characterisation of the oligo saccharides attached to these boar seminal plasma glycoproteins provides the necessary foundation for investigating the potential biological role of PSP-I and PSP-II
glycans.
References
Benoff S (1997) Carbohydrates and fertilization: an overview. Mol Hum Reprod 3: 599-637
Bork P, Beckmann G (1993) The CUB domain. A widespread module in developmentally regulated
proteins. J Mol BioI 231: 539 - 545
Calvete n, Sanz L, Dostalova Z, Tiipfer-Petersen E (1995a) Spermadhesins: sperm-coating proteins
involved in capacitation and zona pellucida binding. Fertilitat 11: 35-40
Calvete n, Mann K, Schafer W, Raida M, Sanz L, Tiipfer-Petersen E (1995b) Boar spermadhesin PSP-II:
location of posttranslational modifications, heterodimer formation with PSP-I glycoforms, and
effect of dimerization on the ligand-binding capabilities of the subunits. FEBS Lett 365: 179-182
Calvete n, Sanz L, Ensslin M, Tiipfer-Petersen E (1996a) Sperm surface proteins. Repr Dom Anim 31:
101-106
Calvete n, Carrera E, Sanz L, Tiipfer-Petersen E (1996b) Boar spermadhesins AQN-l and AQN-3: oligosaccharide and zona-peIIucida binding characteristics. BioI Chern 377: 521-527
Dell A, Morris HR, Easton RL, Panico M, Patankar M, Oehninger S, Koistinen R, Koistinen H, Seppala
M, Clark GF (1995) Structural analysis of the oligo saccharides derived from glycodelin, a human
glycoprotein with potent immunosuppressive and contraceptive activities. J BioI Chern 270:
24116-24126
249
were characterised. Except for a few monoantennary structures, all the oligosacchari des are di- or triantennary glycans sharing a (GlcNAc)z(ManhGlcNAc
(Fuc)GlcNAc core. Each antenna of diantennary structures displays combinations
of
[NeuAca2-61 0_1 [Gala1-310-1 [(Gal!GalNAC)~1-410_I[GlcNAc(Fuca1-3)0_1
~1-(2/4)10_1 Man sequence. A monosialylated oligosaccharide structure bearing
terminal NeuGly instead of NeuAc was also characterised. The third branch of
triantennary structures consist of (Gala1- 3 )0-1 Gal~ 1-4-GlcNAc sequences 131-4linked to the mannose residue or ~1-(3/6)-linked to the outer galactose residue of
the 1-3 antenna. Disialylated glycans display NeuAca2-6Gal~1-4GlcNAc or
NeuAca2-6GalNAc~ 1-4GlcNAc sequences.
Despite being PSP-I/PSP-II heterodimer the major protein of boar seminal
plasma, its function remains elusive. An interesting possibility is that the oligosaccharides participate in PSP-I/PSP-II function. Structural analysis of the oligosaccharides derived from glycodelin, a human glycoprotein with potent immunosuppressive and contraceptive activities, showed that the major non-reducing
epitopes in the complex-type glycans are Gal~1-4GlcNAc (lacNAc), GalNAc~1-4
GlcNAc (lacdiNAc), NeuAca2-6Gal~1-4-GlcNAc (sialylated lacNAc), NeuAc
a2-6GalNAc~1-4-GlcNAc (sialylated lacdiNAc), Gal~1-4(Fuca1-3)GlcNAc
(Lewis X ), and GalNAc~1-4(Fuca1-3)GlcNAc (lacdiNAc analogue ofLewis X ) (Dell
et al. 1995). The authors have put forward the hypothesis that the oligosaccharides bearing sialylated lacNAc or lacdiNAc antennae may manifest immunosuppressive effect by blocking adhesive and activation-related events mediated by
CD22, the human B cell associated receptor, and that oligo saccharides with fucosylated lacdiNAc antennae might block selectin -mediated adhesion [401. Boar
seminal plasma contains immunosuppressive activity associated with 14 kDa
protein(s) (Veselsky el al. 1996). Both, the molecular mass and the type of glycosylation of the PSP-I/PSP-II subunits would support immunosuppressive function
for PSP-I and PSP-II glycoforms. The structural characterisation of the oligo saccharides attached to these boar seminal plasma glycoproteins provides the necessary foundation for investigating the potential biological role of PSP-I and PSP-II
glycans.
References
Benoff S (1997) Carbohydrates and fertilization: an overview. Mol Hum Reprod 3: 599-637
Bork P, Beckmann G (1993) The CUB domain. A widespread module in developmentally regulated
proteins. J Mol BioI 231: 539 - 545
Calvete n, Sanz L, Dostalova Z, Tiipfer-Petersen E (1995a) Spermadhesins: sperm-coating proteins
involved in capacitation and zona pellucida binding. Fertilitat 11: 35-40
Calvete n, Mann K, Schafer W, Raida M, Sanz L, Tiipfer-Petersen E (1995b) Boar spermadhesin PSP-II:
location of posttranslational modifications, heterodimer formation with PSP-I glycoforms, and
effect of dimerization on the ligand-binding capabilities of the subunits. FEBS Lett 365: 179-182
Calvete n, Sanz L, Ensslin M, Tiipfer-Petersen E (1996a) Sperm surface proteins. Repr Dom Anim 31:
101-106
Calvete n, Carrera E, Sanz L, Tiipfer-Petersen E (1996b) Boar spermadhesins AQN-l and AQN-3: oligosaccharide and zona-peIIucida binding characteristics. BioI Chern 377: 521-527
Dell A, Morris HR, Easton RL, Panico M, Patankar M, Oehninger S, Koistinen R, Koistinen H, Seppala
M, Clark GF (1995) Structural analysis of the oligo saccharides derived from glycodelin, a human
glycoprotein with potent immunosuppressive and contraceptive activities. J BioI Chern 270:
24116-24126