Structural and membrane binding analysis of the phox homology domain of phosphoinositide 3-kinase-C2α

Robert V. Stahelin, Dimitrios Karathanassis, Karol S. Bruzik, Michael D. Waterfield, Jerónimo Bravo, Roger L. Williams, Wonhwa Cho

Research output: Contribution to journalArticle

53 Scopus citations

Abstract

Phox homology (PX) domains, which have been identified in a variety of proteins involved in cell signaling and membrane trafficking, have been shown to interact with phosphoinositides (PIs) with different affinities and specificities. To elucidate the structural origin of diverse PI specificities of PX domains, we determined the crystal structure of the PX domain from phosphoinositide 3-kinase C2α (PI3K-C2α), which binds phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2). To delineate the mechanism by which this PX domain interacts with membranes, we measured the membrane binding of the wild type domain and mutants by surface plasmon resonance and monolayer techniques. This PX domain contains a signature PI-binding site that is optimized for PtdIns(4,5)P2 binding. The membrane binding of the PX domain is initiated by nonspecific electrostatic interactions followed by the membrane penetration of hydrophobic residues. Membrane penetration is specifically enhanced by PtdIns(4,5)P2. Furthermore, the PX domain displayed significantly higher PtdIns(4,5)P 2 membrane affinity and specificity when compared with the PI3K-C2αC2 domain, demonstrating that high affinity PtdIns(4,5)P 2 binding was facilitated by the PX domain in full-length PI3K-C2α. Together, these studies provide new structural insight into the diverse PI specificities of PX domains and elucidate the mechanism by which the PI3K-C2α PX domain interacts with PtdIns(4,5)P2-containing membranes and thereby mediates the membrane recruitment of PI3K-C2α.

Original languageEnglish (US)
Pages (from-to)39396-39406
Number of pages11
JournalJournal of Biological Chemistry
Volume281
Issue number51
DOIs
StatePublished - Dec 22 2006
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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    Stahelin, R. V., Karathanassis, D., Bruzik, K. S., Waterfield, M. D., Bravo, J., Williams, R. L., & Cho, W. (2006). Structural and membrane binding analysis of the phox homology domain of phosphoinositide 3-kinase-C2α. Journal of Biological Chemistry, 281(51), 39396-39406. https://doi.org/10.1074/jbc.M607079200