Identification and characterization of the lipid-binding property of GrlR, a locus of enterocyte effacement regulator

Chacko Jobichen, Aaron Z. Fernandis, Adrian Velazquez-Campoy, Ka Yin Leung, Yu Keung Mok, Markus R. Wenk, J. Sivaraman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Lipocalins are a broad family of proteins identified initially in eukaryotes and more recently in Gram-negative bacteria. The functions of lipocalin or lipid-binding proteins are often elusive and very diverse. Recently, we have determined the structure of GrlR (global regulator of LEE repressor), which plays a key role in the regulation of LEE (locus of enterocyte effacement) proteins. GrlR adopts a lipocalin-like fold that is composed of an eight-stranded β-barrel followed by an α-helix at the C-terminus. GrlR has a highly hydrophobic cavity region and could be a potential transporter of lipophilic molecules. To verify this hypothesis, we carried out structure-based analysis of GrlR, determined the structure of the lipid-GrlR complex and measured the binding of lipid to recombinant GrlR by ITC (isothermal titration calorimetry). In addition, we identified phosphatidylglycerol and phosphatidylethanolamine as the endogenously bound lipid species of GrlR using electrospray-ionization MS. Furthermore, we have shown that the lipid-binding property of GrlR is similar to that of its closest lipocalin structural homologue, β-lactoglobulin. Our studies demonstrate the hitherto unknown lipid-binding property of GrlR.

Original languageEnglish
Pages (from-to)191-199
Number of pages9
JournalBiochemical Journal
Volume420
Issue number2
DOIs
StatePublished - 1 Jun 2009
Externally publishedYes

Keywords

  • Global regulator of LEE (locus of enterocyte effacement) repressor (Gr1R)
  • Lipid
  • Lipocalin
  • Type III secretion system (T3SS)
  • β-barrel protein

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