Characterization of recombinant precursor proteins of the human seminal plasma sperm motility inhibitor synthesized in insect cells.
Human seminal plasma sperm motility inhibitor (SPMI) proteins which are exclusively secreted from seminal vesicles, inhibit sperm motility. It is secreted as biologically active 52 kDa and a mixture of 71 and 76 kDa precursor forms, which are identical to semenogelin-I and II (Sg-I and Sg-II), respectively. To understand the molecular mechanism underlying the inhibition of sperm motility by SPMI proteins, we expressed human Sg-I and Sg-II genes in insect cells using a baculovirus system. The baculoviruses expressing full-size Sg-I and Sg-II proteins that were N-terminally-tagged with a hexahistidine were selected, and were infected with Sf 21 cells. The Sg-I and Sg-II proteins were purified from infected cells by column chromatography using Ni-NTA resin 48 h after infection. The full-size Sg-I and Sg-II proteins were obtained in soluble forms. However, they tended to aggregate to form a gel, as expected from naturally occurring semenogelin. Both the purified recombinant Sg-I and Sg-II proteins showed strong SPMI activities with a complete inhibition of sperm motility at 60 units/mg, equivalent to the natural proteins. This production system that permits the generation of purified Sg-I and Sg-II proteins, as well as mutant derivatives, will be helpful for further study on male infertility.
Murakami
J
J
Department of Urology, St. Marianna University School of Medicine, Kanagawa, Japan.
Yoshiike
M
M
Satoh
M
M
Furuichi
Y
Y
Iwamoto
T
T
D000818:Animals; D016367:Baculoviridae; D003429:Cross Reactions; D004926:Escherichia coli / Q000235:genetics; D012739:Gonadal Steroid Hormones / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007313:Insecta / Q000166:cytology / Q000235:genetics* / Q000821:virology; D008297:Male; D015202:Protein Engineering / Q000379:methods; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D029589:Seminal Plasma Proteins; D029607:Seminal Vesicle Secretory Proteins; D013094:Spermatozoa / Q000187:drug effects
D012739:Gonadal Steroid Hormones; D011994:Recombinant Proteins; D029589:Seminal Plasma Proteins; D029607:Seminal Vesicle Secretory Proteins; C424482:seminal vesicle-specific antigen