Spermadhesins are a family of seminal plasma proteins composed of a single CUB domain, which appear to be involved in various aspects of the fertilization process in pigs. PSP-I and PSP-II, the most abundant porcine spermadhesins, occur in seminal plasma as noncovalent heterodimers devoid of heparin-binding capability. Of note is the stability of this dimer, which is significantly affected by physiologically relevant conditions such as Zn2+ ions. Here, we show that PSP-I and PSP-II when separated appear to conserve the overall fold of the CUB domain observed in the crystal structure of the PSP-I/PSP-II heterodimer, as concluded from gel filtration, analytical ultracentrifugation, differential scanning calorimetry, and circular dichroism analyses. However, Zn2+ concentrations in the range of those found in boar seminal plasma induce the unfolding and self-association of PSP-I, apparently as a consequence of the exposure of hydrophobic core residues, whereas they have no effect on PSP-II. Remarkably, Zn2+-denatured and self-associated (but not structured monomeric) PSP-I is retained on a heparin column, resembling the behavior of free PSP-I and homologous spermadhesins of the heparin-binding fraction of boar seminal plasma, which also exhibit different aggregation states. Thus, the modulation of the structural organization and heparin-binding ability of PSP-I by Zn2+ might be a physiological phenomenon in seminal plasma. Study holds ProTherm entries: 20095, 20096, 20097, 20098, 20099, 20100, 20101, 20102, 20103 Extra Details: Spermadhesins, fertilization process, stability of this dimer, Zn2+ ions.
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:52 p.m.
|Number of data points||12|
|Proteins||Major seminal plasma glycoprotein PSP-II ; Major seminal plasma glycoprotein PSP-I ; Major seminal plasma glycoprotein PSP-I ; Major seminal plasma glycoprotein PSP-I|
|Assays/Quantities/Protocols||Experimental Assay: dHcal ionic:ZnCl2: 5 mM ; Experimental Assay: Tm prot_conc:0.5-2 mg/mL, ionic:ZnCl2: 5 mM ; Experimental Assay: Tm ionic:: , prot_conc:0.5-2 mg/mL, details:Additives ZnCl2 (4 mM), ; Experimental Assay: dHcal ionic:: ; Experimental Assay: Tm ionic:: , prot_conc:0.5-2 mg/mL ; Experimental Assay: Tm prot_conc:1 mg/mL, details:Additives ZnCl2 (4 mM),, ionic:: ; Experimental Assay: Tm details:Additives ZnCl2 (1 mM),, ionic:: , prot_conc:1 mg/mL ; Experimental Assay: Tm prot_conc:1 mg/mL, ionic::|
|Libraries||Mutations for sequence A:LDYHACGGRLTDDYGTIFTYKGPKTECVWTLQVDPKYKLLVSIPTLNLTCGKEYVEVLEGAPGSKSLGKFCEGLSILNRGSSGMTVKYKRDSGHPASPYEIIFLRDSQG/B:ARINGPDECGRVIKDTSGSISNTDRQKNLCTWTILMKPDQKVRMAIPYLNLACGKEYVEVFDGLLSGPSYGKLCAGAAIVFLSTANTMTIKYNRISGNSSSPFLIYFYGSSPGSEY|