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Fertilization competence of the egg-coating envelope is regulated by direct interaction of dicalcin and gp41, the Xenopus laevis ZP3.

Miwa N, Ogawa M, Hanaue M, Takamatsu K - Sci Rep (2015)

Bottom Line: Synthetic peptides corresponding to these regions dramatically affected fertilization: treatment with dicalcin- or gp41-derived peptides decreased or increased fertilization rates, respectively.Transmission electron microscopy analysis revealed that the dicalcin-derived peptide induced the formation of a well-organized meshwork, whereas the gp41-derived peptide caused the formation of a significantly disorganized meshwork.These findings indicated that the fertilization competence of the egg-coating envelope is crucially regulated by the direct interaction between dicalcin and gp41.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, School of Medicine, Toho University, Ohmori-nishi 5-21-16, Ohta-ku, Tokyo 143-8540, Japan.

ABSTRACT
Fertilization begins with species-restricted interaction of sperm and the egg-coating envelope, which includes a three-dimensional meshwork of filaments composed of glycoproteins (called ZP proteins). Growing evidence has unveiled the molecular nature of ZP proteins; however, the structural property conferring fertilization competence to the egg-coating envelope remains unknown. Here, we show the molecular mechanism that mediates direct interaction between dicalcin, a novel fertilization-suppressive ZP protein-associated protein, and gp41, a Xenopus laevis ortholog of mammalian ZP3, and subsequently demonstrate the structural basis of the envelope for fertilization competence. The interactive regions between dicalcin and gp41 comprised five and nine amino acid residues within dicalcin and twenty-three within gp41 [corrected]. Synthetic peptides corresponding to these regions dramatically affected fertilization: treatment with dicalcin- or gp41-derived peptides decreased or increased fertilization rates, respectively. Prior application of these peptides caused distinct alterations in the in vivo lectin-staining pattern of the envelope as well. Transmission electron microscopy analysis revealed that the dicalcin-derived peptide induced the formation of a well-organized meshwork, whereas the gp41-derived peptide caused the formation of a significantly disorganized meshwork. These findings indicated that the fertilization competence of the egg-coating envelope is crucially regulated by the direct interaction between dicalcin and gp41.

No MeSH data available.


Dicalcin-and gp41-derived peptides induce distinct nanoscale ZP meshworks. TEM analysis of the VE treated with dcp11 and gpp2.(Upper) Low magnified images of the VE treated with peptides (dcp1 as control, dcp11 and gpp2; 4 μM; n = 3). Note that intensities were enhanced to obtain fine details of ZP filaments. Scale bar: 500 nm. (Lower) Higher magnified images. Scale bar: 30 nm.
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f4: Dicalcin-and gp41-derived peptides induce distinct nanoscale ZP meshworks. TEM analysis of the VE treated with dcp11 and gpp2.(Upper) Low magnified images of the VE treated with peptides (dcp1 as control, dcp11 and gpp2; 4 μM; n = 3). Note that intensities were enhanced to obtain fine details of ZP filaments. Scale bar: 500 nm. (Lower) Higher magnified images. Scale bar: 30 nm.

Mentions: To investigate the fine structural basis underlying the three-dimensional alterations described above, we next used transmission electron microscopy (TEM). TEM analysis revealed that ZP filaments pretreated with dcp11 were arranged parallel to the egg plasma membrane, giving the appearance of a “pin-stripe” pattern (Fig. 4b, dcp11). On the other hand, ZP filaments treated with gpp2 were randomized and many filaments were arranged oblique to the egg plasma membrane, forming a zigzag or occasionally “herring-bone” pattern (Fig.4b, gpp2). These results suggested that treatment with dcp11 and gpp2 caused two distinct nanoscale meshworks that determined whether the VE was fertilization competent (caused by gpp2) or incompetent (caused by dcp11). These structural differences of the VE likely underlie the suppressive action of dicalcin on sperm-binding and sperm-penetration processes in frogs16 and may also be responsible for the variations in fertility observed in many species.


Fertilization competence of the egg-coating envelope is regulated by direct interaction of dicalcin and gp41, the Xenopus laevis ZP3.

Miwa N, Ogawa M, Hanaue M, Takamatsu K - Sci Rep (2015)

Dicalcin-and gp41-derived peptides induce distinct nanoscale ZP meshworks. TEM analysis of the VE treated with dcp11 and gpp2.(Upper) Low magnified images of the VE treated with peptides (dcp1 as control, dcp11 and gpp2; 4 μM; n = 3). Note that intensities were enhanced to obtain fine details of ZP filaments. Scale bar: 500 nm. (Lower) Higher magnified images. Scale bar: 30 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525147&req=5

f4: Dicalcin-and gp41-derived peptides induce distinct nanoscale ZP meshworks. TEM analysis of the VE treated with dcp11 and gpp2.(Upper) Low magnified images of the VE treated with peptides (dcp1 as control, dcp11 and gpp2; 4 μM; n = 3). Note that intensities were enhanced to obtain fine details of ZP filaments. Scale bar: 500 nm. (Lower) Higher magnified images. Scale bar: 30 nm.
Mentions: To investigate the fine structural basis underlying the three-dimensional alterations described above, we next used transmission electron microscopy (TEM). TEM analysis revealed that ZP filaments pretreated with dcp11 were arranged parallel to the egg plasma membrane, giving the appearance of a “pin-stripe” pattern (Fig. 4b, dcp11). On the other hand, ZP filaments treated with gpp2 were randomized and many filaments were arranged oblique to the egg plasma membrane, forming a zigzag or occasionally “herring-bone” pattern (Fig.4b, gpp2). These results suggested that treatment with dcp11 and gpp2 caused two distinct nanoscale meshworks that determined whether the VE was fertilization competent (caused by gpp2) or incompetent (caused by dcp11). These structural differences of the VE likely underlie the suppressive action of dicalcin on sperm-binding and sperm-penetration processes in frogs16 and may also be responsible for the variations in fertility observed in many species.

Bottom Line: Synthetic peptides corresponding to these regions dramatically affected fertilization: treatment with dicalcin- or gp41-derived peptides decreased or increased fertilization rates, respectively.Transmission electron microscopy analysis revealed that the dicalcin-derived peptide induced the formation of a well-organized meshwork, whereas the gp41-derived peptide caused the formation of a significantly disorganized meshwork.These findings indicated that the fertilization competence of the egg-coating envelope is crucially regulated by the direct interaction between dicalcin and gp41.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, School of Medicine, Toho University, Ohmori-nishi 5-21-16, Ohta-ku, Tokyo 143-8540, Japan.

ABSTRACT
Fertilization begins with species-restricted interaction of sperm and the egg-coating envelope, which includes a three-dimensional meshwork of filaments composed of glycoproteins (called ZP proteins). Growing evidence has unveiled the molecular nature of ZP proteins; however, the structural property conferring fertilization competence to the egg-coating envelope remains unknown. Here, we show the molecular mechanism that mediates direct interaction between dicalcin, a novel fertilization-suppressive ZP protein-associated protein, and gp41, a Xenopus laevis ortholog of mammalian ZP3, and subsequently demonstrate the structural basis of the envelope for fertilization competence. The interactive regions between dicalcin and gp41 comprised five and nine amino acid residues within dicalcin and twenty-three within gp41 [corrected]. Synthetic peptides corresponding to these regions dramatically affected fertilization: treatment with dicalcin- or gp41-derived peptides decreased or increased fertilization rates, respectively. Prior application of these peptides caused distinct alterations in the in vivo lectin-staining pattern of the envelope as well. Transmission electron microscopy analysis revealed that the dicalcin-derived peptide induced the formation of a well-organized meshwork, whereas the gp41-derived peptide caused the formation of a significantly disorganized meshwork. These findings indicated that the fertilization competence of the egg-coating envelope is crucially regulated by the direct interaction between dicalcin and gp41.

No MeSH data available.