The Biomineralization Proteome: Protein Complexity for a Complex Bioceramic Assembly Process

Abstract

There are over 62 different biominerals on Earth and a diverse array of organisms that generate these biominerals for survival. This review will introduce the process of biomineralization and the current understanding of the molecular mechanisms of mineral formation, and then comparatively explore the representative secretomes of two well-documented skeletal systems: vertebrate bone (calcium phosphate) and invertebrate mollusk shell (calcium carbonate). It is found that both skeletal secretomes have gross similarities and possess proteins that fall into four functional categories: matrix formers, nucleation assisters, communicators, and remodelers. In many cases the mineral-associated matrix former and nucleation assister sequences in both skeletal systems are unique and possess interactive conserved globular domains, intrinsic disorder, post-translational modifications, sequence redundancy, and amyloid-like aggregation-prone sequences. Together, these molecular features create a protein-based environment that facilitates mineral formation and organization and argue in favor of conserved features that evolve from the mollusk shell to bone. Interestingly, the mollusk shell secretome appears to be more complex compared to that of bone tissue, in that there are numerous protein subcategories that are required for the nucleation and organization of inner (nacre) and outer (prismatic) calcium carbonate regions of the shell. This may reflect the organizational and material requirements of an exoskeletal protective system.

Connexin Mutants Compromise the Lens Circulation and Cause Cataracts through Biomineralization

“…Lens biomineralization might be the key to the formation of cataracts of other etiologies. In other systems/tissues, various proteins participate in initiating the process of mineralization [65]. Thus, in cataracts that do not start through disruption of the lens circulation, the initial step might be the denaturation and/or aggregation of lens proteins that subsequently act as a surface for the deposit of Ca 2+ salts, followed by the growth of mixed aggregates detectable as significant opacities.…”

ProminTools: shedding light on proteins of unknown function in biomineralization with user friendly tools illustrated using mollusc shell matrix protein sequences

“…These biominerals are critical for fitness, playing roles in support, defence, buoyancy, regulation of ion budgets and orientation, among others. Proteins have been found to be associated with many biominerals, and are hypothesised to have a key role in mineral synthesis ( Evans, 2019a ; Evans, 2019b ; Wang & Nilsen-Hamilton, 2012 ). In some cases the roles of such proteins is relatively well understood, and some of the best studies examples come from molluscs ( Song et al, 2019 ).…”

Molecular Characterization of a Novel Shell Matrix Protein With PDZ Domain From Mytilus coruscus

“…As highlighted previously, assembly of a biochemical framework is essential for shell formation ( Nudelman et al, 2006 ; Evans, 2019 ), and the formation of the framework layer in mollusk shells relies on specific matrix-forming proteins, such as silk-like proteins and chitin-binding proteins ( Evans, 2019 ). In this study, 19 proteins were identified by the pull-down technique combined with LC-MS/MS analysis, providing a set of candidate proteins that interact with PDCP-1.…”