Effect of lipid head groups on double-layered two-dimensional crystals formed by aquaporin-0

Richard Kevin Hite, Po-Lin Chiu, Jan Michael Schuller, Thomas Walz

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Aquaporin-0 (AQP0) is a lens-specific water channel that also forms membrane junctions. Reconstitution of AQP0 with dimyristoyl phosphatidylcholine (DMPC) and E. coli polar lipids (EPL) yielded well-ordered, double-layered two-dimensional (2D) crystals that allowed electron crystallographic structure determination of the AQP0-mediated membrane junction. The interacting tetramers in the two crystalline layers are exactly in register, resulting in crystals with p422 symmetry. The high-resolution density maps also allowed modeling of the annular lipids surrounding the tetramers. Comparison of the DMPC and EPL bilayers suggested that the lipid head groups do not play an important role in the interaction of annular lipids with AQP0. We now reconstituted AQP0 with the anionic lipid dimyristoyl phosphatidylglycerol (DMPG), which yielded a mixture of 2D crystals with different symmetries. The different crystal symmetries result from shifts between the two crystalline layers, suggesting that the negatively charged PG head group destabilizes the interaction between the extracellular AQP0 surfaces. Reconstitution of AQP0 with dimyristoyl phosphatidylserine (DMPS), another anionic lipid, yielded crystals that had the usual p422 symmetry, but the crystals showed a pH-dependent tendency to stack through their cytoplasmic surfaces. Finally, AQP0 failed to reconstitute into membranes that were composed of more than 40% dimyristoyl phosphatidic acid (DMPA). Hence, although DMPG, DMPS, and DMPA are all negatively charged lipids, they have very different effects on AQP0 2D crystals, illustrating the importance of the specific lipid head group chemistry beyond its mere charge.

Original languageEnglish (US)
Article numbere0117371
JournalPLoS One
Volume10
Issue number1
DOIs
StatePublished - Jan 30 2015
Externally publishedYes

Fingerprint

aquaporins
crystals
Lipids
Crystals
lipids
Crystal symmetry
Phosphatidic Acids
phosphatidylserines
Phosphatidylserines
phosphatidylglycerols
Membranes
Phosphatidylcholines
phosphatidylcholines
Escherichia coli
Crystalline materials
aquaporin 0
Aquaporins
lipid bilayers
Lipid bilayers
acids

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Effect of lipid head groups on double-layered two-dimensional crystals formed by aquaporin-0. / Hite, Richard Kevin; Chiu, Po-Lin; Schuller, Jan Michael; Walz, Thomas.

In: PLoS One, Vol. 10, No. 1, e0117371, 30.01.2015.

Research output: Contribution to journalArticle

Hite, Richard Kevin ; Chiu, Po-Lin ; Schuller, Jan Michael ; Walz, Thomas. / Effect of lipid head groups on double-layered two-dimensional crystals formed by aquaporin-0. In: PLoS One. 2015 ; Vol. 10, No. 1.
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