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NleG Type 3 Effectors from Enterohaemorrhagic Escherichia coli Are U-Box E3 Ubiquitin Ligases.

Authors :
Bin Wu
Skarina, Tatiana
Yee, Adelinda
Jobin, Marie-Claude
DiLeo, Rosa
Semesi, Anthony
Fares, Christophe
Lemak, Alexander
Coombes, Brian K.
Arrowsmith, Cheryl H.
Singer, Alexander U.
Savchenko, Alexei
Source :
PLoS Pathogens; Jun2010, Vol. 6 Issue 6, p1-17, 17p, 1 Black and White Photograph, 2 Diagrams, 2 Charts, 3 Graphs
Publication Year :
2010

Abstract

NleG homologues constitute the largest family of type 3 effectors delivered by pathogenic E. coli, with fourteen members in the enterohaemorrhagic (EHEC) O157:H7 strain alone. Identified recently as part of the non-LEE-encoded (Nle) effector set, this family remained uncharacterised and shared no sequence homology to other proteins including those of known function. The C-terminal domain of NleG2-3 (residues 90 to 191) is the most conserved region in NleG proteins and was solved by NMR. Structural analysis of this structure revealed the presence of a RING finger/U-box motif. Functional assays demonstrated that NleG2-3 as well as NleG5-1, NleG6-2 and NleG9′ family members exhibited a strong autoubiquitination activity in vitro; a characteristic usually expressed by eukaryotic ubiquitin E3 ligases. When screened for activity against a panel of 30 human E2 enzymes, the NleG2-3 and NleG5-1 homologues showed an identical profile with only UBE2E2, UBE2E3 and UBE2D2 enzymes supporting NleG activity. Fluorescence polarization analysis yielded a binding affinity constant of 56 ± μM for the UBE2D2/NleG5-1 interaction, a value comparable with previous studies on E2/E3 affinities. The UBE2D2 interaction interface on NleG2-3 defined by NMR chemical shift perturbation and mutagenesis was shown to be generally similar to that characterised for human RING finger ubiquitin ligases. The alanine substitutions of UBE2D2 residues Arg5 and Lys63, critical for activation of eukaryotic E3 ligases, also significantly decreased both NleG binding and autoubiquitination activity. These results demonstrate that bacteria-encoded NleG effectors are E3 ubiquitin ligases analogous to RING finger and U-box enzymes in eukaryotes. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
15537366
Volume :
6
Issue :
6
Database :
Complementary Index
Journal :
PLoS Pathogens
Publication Type :
Academic Journal
Accession number :
52159957
Full Text :
https://doi.org/10.1371/journal.ppat.1000960