Budding and asymmetric protein microcompartmentation in giant vesicles containing two aqueous phases

M. Scott Long, Ann Sofie Cans, Christine Dolan Keating

Research output: Contribution to journalArticlepeer-review

85 Scopus citations

Abstract

We report the effect of external osmolarity on giant lipid vesicles containing an aqueous two-phase system (ATPS GVs). The ATPS, which is comprised of poly(ethyleneglycol) [PEG], dextran, and water, serves as a primitive model of the macromolecularly crowded environment of the cytoplasm. Coexisting PEG-rich and dextran-rich aqueous phases provide chemically dissimilar microenvironments, enabling local differences in protein concentration to be maintained within single ATPS GVs. The degree of biomolecule microcompartmentation can be increased by exposing the ATPS GVs to a hypertonic external solution, which draws water out of the vesicles, concentrating the polymers. Enrichment of a protein, soybean agglutinin, in the dextran-rich phase improves from 2.3-fold to 10-fold with an increase in external osmolarity from 100 to 200 mmol/kg. In some cases, budding occurs, with the bud(s) formed by partial expulsion of one of the two polymer-rich aqueous phases. Budding results in asymmetry in the internal polymer and biomolecule composition, giving rise to polarity in these primitive model cells. Budding is observed with increasing frequency as external ionic strength increases, when membrane elasticity permits, and can be reversed by decreasing external osmolarity. We note that the random symmetry-breaking induced by simple osmotic shrinkage resulted in polarity in both the structure and internal protein distribution in these primitive model cells. Budding in ATPS-containing GVs thus offers an experimental model system for investigating the effects of biochemical asymmetry on the length scale of single cells.

Original languageEnglish (US)
Pages (from-to)756-762
Number of pages7
JournalJournal of the American Chemical Society
Volume130
Issue number2
DOIs
StatePublished - Jan 16 2008

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Fingerprint Dive into the research topics of 'Budding and asymmetric protein microcompartmentation in giant vesicles containing two aqueous phases'. Together they form a unique fingerprint.

Cite this