Phosphatidylethanolamine of Helicobacter pylori functions as a steroid-binding lipid in the assimilation of free cholesterol and 3β-hydroxl steroids into the bacterial cell membrane

Hirofumi Shimomura, Kouichi Hosoda, Shunji Hayashi, Kenji Yokota, Yoshikazu Hirai

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

One of the unique features of Helicobacter pylori is its ability to assimilate free-cholesterol (FC) into its membranes. Via FC assimilation, H. pylori strengthens the membrane lipid barrier and/or evades the host immune system. No previous studies, however, have investigated the FC uptake mechanisms of the H. pylori cell. Phosphatidylethanolamine (PE) is the most prevalent lipid component of bacteria, including H. pylori, but the function of PE remains unclear. We were therefore interested in H. pylori PE (HpPE) and investigated the interaction of its PE with cholesterols. The PE isolated from H. pylori underwent a unique molecular interaction with FC, cholesterol ester (CE), and 2,6-di-O-methyl-β-cyclodextrin (dMßCD), a sterol solubilizer. HpPE interacted not only with the FC molecule, but also with the FC-dMβCD inclusion complex. In contrast, Escherichia coli PE (EcPE), prepared as a reference PE, seemed to bind only FC, and only via a hydrophobic interaction, without binding dMβCD. HpPE was clearly more potent than EcPE in binding FC. Intriguingly, HpPE had a negligible affinity for CE, while EcPE had a high affinity for CE, comparable to its affinity for FC. Further, HpPE interacted with 3β-OH steroids, pregnenolone and dehydroepiandrosterone, in the absence of dMβCD. Gas chromatogram-mass spectrometry (GC-MS) and liquid chromatographymass spectrometry (LC-MS) analyses revealed that the fatty acid compositions of HpPE were quite distinct from those of EcPE, and the C14:0 fatty acid in the HpPE molecule was found to be significant in binding FC selectively. These results indicate that PE is a key candidate of nonesterified steroid-binding lipids in H. pylori.

Original languageEnglish
Pages (from-to)2658-2667
Number of pages10
JournalJournal of bacteriology
Volume194
Issue number10
DOIs
Publication statusPublished - May 2012

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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