Abstract
Background: Biological mineral formation (biomineralization) proceeds in specialized compartments often bounded by a lipid bilayer membrane. Currently, the role of membranes in biomineralization is hardly understood. Results: Investigating biomineralization of SiO2 (silica) in diatoms we identified Silicanin-1 (Sin1) as a conserved diatom membrane protein present in silica deposition vesicles (SDVs) of Thalassiosira pseudonana. Fluorescence microscopy of GFP-tagged Sin1 enabled, for the first time, to follow the intracellular locations of a biomineralization protein during silica biogenesis in vivo. The analysis revealed incorporation of the N-terminal domain of Sin1 into the biosilica via association with the organic matrix inside the SDVs. In vitro experiments showed that the recombinant N-terminal domain of Sin1 undergoes pH-triggered assembly into large clusters, and promotes silica formation by synergistic interaction with long-chain polyamines. Conclusions: Sin1 is the first identified SDV transmembrane protein, and is highly conserved throughout the diatom realm, which suggests a fundamental role in the biomineralization of diatom silica. Through interaction with long-chain polyamines, Sin1 could serve as a molecular link by which the SDV membrane exerts control on the assembly of biosilica-forming organic matrices in the SDV lumen.
Original language | English |
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Article number | 65 |
Pages (from-to) | 1-16 |
Journal | BMC Biology |
Volume | 15 |
Issue number | 1 |
DOIs | |
Publication status | Published - 24 Jul 2017 |
Keywords
- Biomineralization vesicles
- Cryo-TEM
- Diatom biosilica
- Exocytosis
- Protein self-assembly
- Silica formation activity
- Time-lapse confocal fluorescence microscopy
- Transmembrane protein
- Vesicle biogenesis
- Membrane Proteins/genetics
- Diatoms/genetics
- RNA, Algal/genetics
- Silicon Dioxide/metabolism
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Center for Multiscale Electron Microscopy (CMEM)
Heiner Friedrich (Manager), Rick Joosten (Education/research officer), Pauline Schmit (Education/research officer), Ingeborg Schreur - Piet (Other) & Anne Spoelstra (Education/research officer)
Physical ChemistryFacility/equipment: Research lab