Silicanin-1 is a conserved diatom membrane protein involved in silica biomineralization

A. Kotzsch, P. Gröger, D. Pawolski, P.H.H. Bomans, N.A.J.M. Sommerdijk, M. Schlierf, N. Kröger

Research output: Contribution to journalArticleAcademicpeer-review

23 Citations (Scopus)
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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 languageEnglish
Article number65
Pages (from-to)1-16
JournalBMC Biology
Volume15
Issue number1
DOIs
Publication statusPublished - 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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