A common ‘aggregation‐prone’ interface possibly participates in the self‐assembly of human zona pellucida proteins

Abstract

Human zona pellucida (ZP) is composed of four glycoproteins, namely ZP1, ZP2, ZP3 and ZP4. ZP proteins form heterodimers, which are incorporated into filaments through a common bipartite polymerizing component, designated as the ZP domain. The latter is composed of two individually folded subdomains, named ZP-N and ZP-C. Here, we have synthesized six 'aggregation-prone' peptides, corresponding to a common interface of human ZP2, ZP3 and ZP4. Experimental results utilizing electron microscopy, X-ray diffraction, ATR FT-IR spectroscopy and polarizing microscopy indicate that these peptides self-assemble forming fibrils with distinct amyloid-like features. Finally, by performing detailed modeling and docking, we attempt to shed some light in the self-assembly mechanism of human ZP proteins.

Cryo‐EM structure of native human uromodulin, a zona pellucida module polymer

“…The first detailed structure of a polymeric ZP module protein reveals a unique filament architecture whose features, to the best of our knowledge, do not resemble those of any previously reported biological polymer. In particular, the structural information reported in this study clearly shows that, unlike hypothesized in the case of egg coat proteins (Jovine et al , 2006; Egge et al , 2015; Okumura et al , 2015; Louros et al , 2016), UMOD neither polymerizes by forming an amyloid cross‐β structure nor assembles through contacts that mostly involve the ZP‐N domain or, alternatively, ZP‐C. Instead, an unprecedented interlocked configuration of ZP‐N and ZP‐C domains forms the basis of the filament core.…”

Heterotypic interactions in amyloid function and disease

“…The former has been shown to promote unilateral nucleation of IAPP, albeit with a lower efficiency compared to homologous assembly, whereby these proteins harbour stretches sharing sequence homology [172]. Several additional proteins have been associated to templated amyloid cross-talk via sharing of common structural architectures [161,[173][174][175], with the list expanding even to cases of functional amyloids [176][177][178][179][180][181][182]. Finally, cross-seeding and heterotypic co-aggregation has also been demonstrated in cancer-associated aggregation pathologies, where mutant p53 causes sequence-dependent co-deposition of its homologs p63 and p73 by virtue of their similar APRs [183][184][185].…”

Functional Amyloids in Reproduction

“…In further support that amyloidogenesis may drive ZP matrix formation and function are studies of human ZP proteins. Peptides corresponding to regions of human ZP proteins implicated in a critical β-strand interphase involved in ZP formation assemble into amyloids [ 46 , 47 ]. In all ZP proteins examined, none possess a classic prion-like domain with Q/N-rich regions but instead contain multiple short amino acid stretches with predicted inherent amyloidogenic propensity as determined by the AmylPred2 algorithm [ 41 ].…”