Crystallization of the large membrane protein complex photosystem i in a microfluidic channel

Bahige G. Abdallah, Christopher Kupitz, Petra Fromme, Alexandra Ros

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Traditional macroscale protein crystallization is accomplished nontrivially by exploring a range of protein concentrations and buffers in solution until a suitable combination is attained. This methodology is time-consuming and resource-intensive, hindering protein structure determination. Even more difficulties arise when crystallizing large membrane protein complexes such as photosystem I (PSI) due to their large unit cells dominated by solvent and complex characteristics that call for even stricter buffer requirements. Structure determination techniques tailored for these "difficult to crystallize" proteins such as femtosecond nanocrystallography are being developed yet still need specific crystal characteristics. Here, we demonstrate a simple and robust method to screen protein crystallization conditions at low ionic strength in a microfluidic device. This is realized in one microfluidic experiment using low sample amounts, unlike traditional methods where each solution condition is set up separately. Second harmonic generation microscopy via second-order nonlinear imaging of chiral crystals (SONICC) was applied for the detection of nanometer- and micrometer-sized PSI crystals within microchannels. To develop a crystallization phase diagram, crystals imaged with SONICC at specific channel locations were correlated to protein and salt concentrations determined by numerical simulations of the time-dependent diffusion process along the channel. Our method demonstrated that a portion of the PSI crystallization phase diagram could be reconstructed in excellent agreement with crystallization conditions determined by traditional methods. We postulate that this approach could be utilized to efficiently study and optimize crystallization conditions for a wide range of proteins that are poorly understood to date.

Original languageEnglish
Pages (from-to)10534-10543
Number of pages10
JournalACS Nano
Volume7
Issue number12
DOIs
Publication statusPublished - Dec 23 2013

Fingerprint

Crystallization
Microfluidics
Membrane Proteins
crystallization
membranes
proteins
Proteins
Membranes
Photosystem I Protein Complex
Crystals
crystals
Phase diagrams
Buffers
buffers
Imaging techniques
phase diagrams
Harmonic generation
Microchannels
Ionic strength
microfluidic devices

Keywords

  • concentration gradients
  • membrane protein
  • numerical simulation
  • SONICC

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)
  • Physics and Astronomy(all)

Cite this

Crystallization of the large membrane protein complex photosystem i in a microfluidic channel. / Abdallah, Bahige G.; Kupitz, Christopher; Fromme, Petra; Ros, Alexandra.

In: ACS Nano, Vol. 7, No. 12, 23.12.2013, p. 10534-10543.

Research output: Contribution to journalArticle

Abdallah, Bahige G. ; Kupitz, Christopher ; Fromme, Petra ; Ros, Alexandra. / Crystallization of the large membrane protein complex photosystem i in a microfluidic channel. In: ACS Nano. 2013 ; Vol. 7, No. 12. pp. 10534-10543.
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