Zinc ions induce the unfolding and self-association of boar spermadhesin PSP-I, a protein with a single CUB domain architecture, and promote its binding to heparin.


Abstract

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.

Submission Details

ID: SpqFXMLo3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:52 p.m.

Version: 1

Publication Details
Campanero-Rhodes MA;Menéndez M;Saiz JL;Sanz L;Calvete JJ;Solís D,Biochemistry (2006) Zinc ions induce the unfolding and self-association of boar spermadhesin PSP-I, a protein with a single CUB domain architecture, and promote its binding to heparin. PMID:16819821
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P
 

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)


Relevant PDB Entries

Structure ID Release Date Resolution Structure Title
1SPP 1998-06-24 2.4 THE CRYSTAL STRUCTURES OF TWO MEMBERS OF THE SPERMADHESIN FAMILY REVEAL THE FOLDING OF THE CUB DOMAIN

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Major seminal plasma glycoprotein PSP-II P35496 PSP2_PIG
100.0 Major seminal plasma glycoprotein PSP-I P35495 PSP1_PIG