Mammalian gamete fusion depends on the inhibition of ovastacin by fetuin-B

Stöcker, Walter; Karmilin, Konstantin; Hildebrand, André; Westphal, Hagen; Yiallouros, Irene; Weiskirchen, Ralf; Dietzel, Eileen; Floehr, Julia; Jahnen‐Dechent, Willi

doi:10.1515/hsz-2014-0189

Cited by 25 publications

(23 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By contrast, fetuin-B deficient mice are female infertile due to premature zona pellucida ‘hardening’, which is caused by ovastacin activity in unfertilized eggs. In wild type mice the activity of spuriously released ovastacin is inhibited by micromolar concentrations of the plasma protein fetuin-B in the follicular fluid until after fertilization, when complete degranulation of oocytes releases large amounts of ovastacin, which override the fetuin-B inhibition 2,3 .…”

Section: Introductionmentioning

confidence: 99%

Mammalian plasma fetuin-B is a selective inhibitor of ovastacin and meprin metalloproteinases

Karmilin

Schmitz

Kuske

et al. 2019

Sci Rep

Self Cite

View full text Add to dashboard Cite

Vertebrate fetuins are multi-domain plasma-proteins of the cystatin-superfamily. Human fetuin-A is also known as AHSG, α2-Heremans-Schmid-glycoprotein. Gene-knockout in mice identified fetuin-A as essential for calcified-matrix-metabolism and bone-mineralization. Fetuin-B deficient mice, on the other hand, are female infertile due to zona pellucida ‘hardening’ caused by the metalloproteinase ovastacin in unfertilized oocytes. In wildtype mice fetuin-B inhibits the activity of ovastacin thus maintaining oocytes fertilizable. Here we asked, if fetuins affect further proteases as might be expected from their evolutionary relation to single-domain-cystatins, known as proteinase-inhibitors. We show that fetuin-A is not an inhibitor of any tested protease. In stark contrast, the closely related fetuin-B selectively inhibits astacin-metalloproteinases such as meprins and ovastacin, but not astacins of the tolloid-subfamily, nor any other proteinase. The analysis of fetuin-B expressed in various mammalian cell types, insect cells, and truncated fish-fetuin expressed in bacteria, showed that the cystatin-like domains alone are necessary and sufficient for inhibition. This report highlights fetuin-B as a specific antagonist of ovastacin and meprin-metalloproteinases. Control of ovastacin was shown to be indispensable for female fertility. Meprin inhibition, on the other hand, renders fetuin-B a potential key-player in proteolytic networks controlling angiogenesis, immune-defense, extracellular-matrix-assembly and general cell-signaling, with implications for inflammation, fibrosis, neurodegenerative disorders and cancer.

show abstract

Section: Introductionmentioning

confidence: 99%

Mammalian plasma fetuin-B is a selective inhibitor of ovastacin and meprin metalloproteinases

Karmilin

Schmitz

Kuske

et al. 2019

Sci Rep

Self Cite

View full text Add to dashboard Cite

show abstract

“…By contrast, meprins, crayfish astacin, nephrosin from cyprinid fishes, and ovastacin are strongly inhibited by fetuin-B forms from mammals, which are strictly selective for astacins 33–36 , and by fish fetuin, which acts as the physiological antagonist of nephrosin 37 . By blocking ovastacin, fetuin-B prevents premature hardening of the zona pellucida and maintains female fertility 26,33,34 . Fetuin-B belongs to the I25 family of peptidase inhibitors according to the MEROPS database of peptidases and inhibitors (www.ebi.ac.uk/merops) 7 .…”

Section: Introductionmentioning

confidence: 99%

The C-terminal region of human plasma fetuin-B is dispensable for the raised-elephant-trunk mechanism of inhibition of astacin metallopeptidases

Guevara

Körschgen

Cuppari

et al. 2019

Sci Rep

Self Cite

View full text Add to dashboard Cite

Human fetuin-B plays a key physiological role in human fertility through its inhibitory action on ovastacin, a member of the astacin family of metallopeptidases. The inhibitor consists of tandem cystatin-like domains (CY1 and CY2), which are connected by a linker containing a “CPDCP-trunk” and followed by a C-terminal region (CTR) void of regular secondary structure. Here, we solved the crystal structure of the complex of the inhibitor with archetypal astacin from crayfish, which is a useful model of human ovastacin. Two hairpins from CY2, the linker, and the tip of the “legumain-binding loop” of CY1 inhibit crayfish astacin following the “raised-elephant-trunk mechanism” recently reported for mouse fetuin-B. This inhibition is exerted by blocking active-site cleft sub-sites upstream and downstream of the catalytic zinc ion, but not those flanking the scissile bond. However, contrary to the mouse complex, which was obtained with fetuin-B nicked at a single site but otherwise intact, most of the CTR was proteolytically removed during crystallization of the human complex. Moreover, the two complexes present in the crystallographic asymmetric unit diverged in the relative arrangement of CY1 and CY2, while the two complexes found for the mouse complex crystal structure were equivalent. Biochemical studies in vitro confirmed the differential cleavage susceptibility of human and mouse fetuin-B in front of crayfish astacin and revealed that the cleaved human inhibitor blocks crayfish astacin and human meprin α and β only slightly less potently than the intact variant. Therefore, the CTR of animal fetuin-B orthologs may have a function in maintaining a particular relative orientation of CY1 and CY2 that nonetheless is dispensable for peptidase inhibition.

show abstract

“…Sperm Acrosomal SLLP1 Binding protein (ovastacin) has been reported to spatially localize to both the oolemma (Sachdev et al ., ) and cortical granules (Burkart et al ., ; Pires et al ., ) with different possible functions ascribed to the proteins in these locations. Before the cortical reaction, the enzymatic activity of SAS1B has been shown to be mediated by fetuin‐B (Dietzel et al ., ; Stocker et al ., ). Eight lines of evidence reveal the strong binding between SLLP1 and SAS1B, which in turn support the hypothesis that SLLP1 binding to the oocyte surface is mediated by SAS1B.…”

Section: Resultsmentioning

confidence: 97%

“…Knockout (Burkart et al ., ; Sachdev et al ., ) of the SLLP1 oolemmal‐binding partner protein SAS1B in mice resulted in sub‐fertility. In addition, SAS1B protein (ovastacin) has also been demonstrated to localize in cortical granules in the sub‐oolemmal cytoplasm (Pires et al ., ) with ZP2‐cleavage activity (Burkart et al ., ; Avella et al ., ) that could be inhibited by fetuin‐B (Dietzel et al ., ; Stocker et al ., ), which reflects its role in the block to polyspermy following fertilization. Moreover, our recent study shows the presence of six alternative splice variants for SAS1B (Sachdev et al ., ), which may relate to the versatile roles this protein plays during fertilization.…”

Section: Introductionmentioning

confidence: 99%

Sperm Lysozyme-Like Protein 1 (SLLP1), an intra-acrosomal oolemmal-binding sperm protein, reveals filamentous organization in protein crystal form

et al. 2015

View full text Add to dashboard Cite

Sperm Lysozyme-Like Protein 1 (SLLP1) is one of the lysozyme-like proteins predominantly expressed in mammalian testes that lacks bacteriolytic activity, localizes in the sperm acrosome, and exhibits high affinity for an oolemmal receptor, SAS1B. The crystal structure of mouse SLLP1 (mSLLP1) was determined at 2.15Å resolution. mSLLP1 monomer adopts a structural fold similar to that of chicken/mouse lysozymes retaining all four canonical disulfide bonds. mSLLP1 is distinct from c-lysozyme by substituting two essential catalytic residues (E35T/D52N), exhibiting different surface charge distribution, and by forming helical filaments approximately 75Å in diameter with a 25Å central pore comprised of six monomers per helix turn repeating every 33Å. Cross-species alignment of all reported SLLP1 sequences revealed a set of invariant surface regions comprising a characteristic fingerprint uniquely identifying SLLP1 from other c-lysozyme family members. The fingerprint surface regions reside around the lips of the putative glycan binding groove including three polar residues (Y33/E46/H113). A flexible salt bridge (E46-R61) was observed covering the glycan binding groove. The conservation of these regions may be linked to their involvement in oolemmal protein binding. Interaction between SLLP1 monomer and its oolemmal receptor SAS1B was modeled using protein-protein docking algorithms, utilizing the SLLP1 fingerprint regions along with the SAS1B conserved surface regions. This computational model revealed complementarity between the conserved SLLP1/SAS1B interacting surfaces supporting the experimentally-observed SLLP1/SAS1B interaction involved in fertilization.

show abstract

Mammalian gamete fusion depends on the inhibition of ovastacin by fetuin-B

Cited by 25 publications

References 5 publications

Mammalian plasma fetuin-B is a selective inhibitor of ovastacin and meprin metalloproteinases

Mammalian plasma fetuin-B is a selective inhibitor of ovastacin and meprin metalloproteinases

The C-terminal region of human plasma fetuin-B is dispensable for the raised-elephant-trunk mechanism of inhibition of astacin metallopeptidases

Sperm Lysozyme-Like Protein 1 (SLLP1), an intra-acrosomal oolemmal-binding sperm protein, reveals filamentous organization in protein crystal form

Contact Info

Product

Resources

About