Recombinant porcine zona pellucida glycoproteins expressed in Sf9 cells bind to bovine sperm but not to porcine sperm.
The zona pellucida, which surrounds the mammalian oocyte, consists of the ZPA, ZPB, and ZPC glycoproteins and plays roles in species-selective sperm-egg interactions via its carbohydrate moieties. In the pig, this activity is conferred by tri- and tetraantennary complex type chains; in cattle, it is conferred by a chain of 5 mannose residues. In this study, porcine zona glycoproteins were expressed as secreted forms, using the baculovirus-Sf9 insect cell system. The sperm binding activities of the recombinant proteins were examined in three different assays. The assays clearly demonstrated that recombinant ZPB bound bovine sperm weakly but did not bind porcine sperm; when recombinant ZPC was also present, bovine sperm binding activity was greatly increased, but porcine sperm still was not bound. The major sugar chains of ZPB were pauci and high mannose type chains that were similar in structure to the major neutral N-linked chain of the bovine zona. In fact, the nonreducing terminal alpha-mannose residues were necessary for the sperm binding activity. These results show that the carbohydrate moieties of zona glycoproteins, but not the polypeptide moieties, play an essential role in species-selective recognition of porcine and bovine sperm. Moreover, Asn to Asp mutations at either of two of the N-glycosylation sites of ZPB, residue 203 or 220, significantly reduced the sperm binding activity of the ZPB/ZPC mixture, whereas a similar mutation at the third N-glycosylation site, Asn-333, had no effect on binding. These results suggest that the N-glycans located in the N-terminal half of the ZP domain of porcine ZPB are involved in sperm-zona binding.
Yonezawa
Naoto
N
Graduate School of Science and Technology, Department of Chemistry, Faculty of Science, Chiba University. Japan.
Kudo
Katsuyasu
K
Terauchi
Hirotomo
H
Kanai
Saeko
S
Yoda
Naoto
N
Tanokura
Masaru
M
Ito
Kosuke
K
Miura
Kin-ichiro
K
Katsumata
Toshiyuki
T
Nakano
Minoru
M
D000818:Animals; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002417:Cattle; D004527:Egg Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D006031:Glycosylation; D015151:Immunoblotting; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism*; D013045:Species Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013094:Spermatozoa / Q000378:metabolism*; D018411:Spodoptera / Q000378:metabolism; D013329:Structure-Activity Relationship; D013552:Swine / Q000235:genetics*; D014162:Transfection; D000072216:Zona Pellucida Glycoproteins
D004527:Egg Proteins; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D011134:Polysaccharides; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D000072216:Zona Pellucida Glycoproteins; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase