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Analysis of the stability of the spermadhesin PSP-I/PSP-II heterodimer. Effects of Zn2+ and acidic pH
- Source :
- FEBS Journal. 272:5663-5670
- Publication Year :
- 2005
- Publisher :
- Wiley, 2005.
-
Abstract
- Spermadhesins are a family of 12-16 kDa proteins with a single CUB domain. PSP-I and PSP-II, the most abundant boar spermadhesins, are present in seminal plasma as a noncovalent heterodimer. Dimerization markedly affects the binding ability of the subunits. Notably, heparin and mannose 6-phosphate binding abilities of PSP-II are abolished, indicating that the corresponding binding sites may be located at (or near) the dimer interface. Pursuing the hypothesis that cryptic binding sites in PSP-I/PSP-II may be exposed in specific physiological environments, we examined the influence of Zn2+ and acidic pH on the heterodimer stability. According to near-UV CD spectra, the core native fold is preserved in the presence of physiological concentrations of Zn2+, a cation unusually abundant in boar seminal plasma. However, the thermostability of the heterodimer decreases significantly, as observed by CD and differential scanning calorimetry. The effect is Zn2+-specific and is reversed by EDTA. Destabilization is also observed at acidic pH. Gel filtration analysis using radioiodinated PSP-I/PSP-II reveals that dissociation of the heterodimer at low (nanomolar) protein concentrations is promoted by both Zn2+ and acidic pH. Although the integrity of the heterodimer in seminal plasma seems to be guaranteed by its high concentration, dissociation may be facilitated in the female genital tract because of dilution of the protein in the intraluminal fluids of the cervix and the uterus, and the acidic fluid of the uterotubal junction. Such a mechanism may be relevant in the regulation of uterine immune reactions.
- Subjects :
- Protein Denaturation
BOAR
Cations, Divalent
Swine
Dimer
Size-exclusion chromatography
Mannose
Biochemistry
Dissociation (chemistry)
chemistry.chemical_compound
Animals
Binding site
Protein Structure, Quaternary
Molecular Biology
Thermostability
Calorimetry, Differential Scanning
Circular Dichroism
Seminal Plasma Proteins
Cell Biology
Hydrogen-Ion Concentration
CUB domain
eye diseases
Zinc
chemistry
Chromatography, Gel
Thermodynamics
Acids
Dimerization
Ultracentrifugation
Protein Binding
Subjects
Details
- ISSN :
- 17424658 and 1742464X
- Volume :
- 272
- Database :
- OpenAIRE
- Journal :
- FEBS Journal
- Accession number :
- edsair.doi.dedup.....79b6b88a67719778ad2f7858cfba742a