Structural adaptation of tooth enamel protein amelogenin in the presence of SDS micelles

Karthik Balakrishna Chandrababu, Kaushik Dutta, Sowmya Bekshe Lokappa, Moise Ndao, John Spencer Evans, Janet Moradian-Oldak

Research output: Contribution to journalArticle

Abstract

Amelogenin, the major extracellular matrix protein of developing tooth enamel is intrinsically disordered. Through its interaction with other proteins and mineral, amelogenin assists enamel biomineralization by controlling the formation of highly organized enamel crystal arrays. We used circular dichroism (CD), dynamic light scattering (DLS), fluorescence, and NMR spectroscopy to investigate the folding propensity of recombinant porcine amelogenin rP172 following its interaction with SDS, at levels above critical micelle concentration. The rP172-SDS complex formation was confirmed by DLS, while an increase in the structure moiety of rP172 was noted through CD and fluorescence experiments. Fluorescence quenching analyses performed on several rP172 mutants where all but one Trp was replaced by Tyr at different sequence regions confirmed that the interaction of amelogenin with SDS micelles occurs via the N-terminal region close to Trp25 where helical segments can be detected by NMR. NMR spectroscopy and structural refinement calculations using CS-Rosetta modeling confirm that the highly conserved N-terminal domain is prone to form helical structure when bound to SDS micelles. Our findings reported here reveal interactions leading to significant changes in the secondary structure of rP172 upon treatment with SDS. These interactions may reflect the physiological relevance of the flexible nature of amelogenin and its sequence specific helical propensity that might enable it to structurally adapt with charged and potential targets such as cell surface, mineral, and other proteins during enamel biomineralization.

Original languageEnglish (US)
Pages (from-to)525-535
Number of pages11
JournalBiopolymers
Volume101
Issue number5
DOIs
StatePublished - May 2014

Keywords

  • CS-Rosetta
  • SDS
  • amelogenin
  • enamel
  • intrinsically disordered protein

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Biomaterials
  • Organic Chemistry

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  • Cite this

    Chandrababu, K. B., Dutta, K., Lokappa, S. B., Ndao, M., Evans, J. S., & Moradian-Oldak, J. (2014). Structural adaptation of tooth enamel protein amelogenin in the presence of SDS micelles. Biopolymers, 101(5), 525-535. https://doi.org/10.1002/bip.22415