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

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±2 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

Hypertension and migraine comorbidity: prevalence and risk of cerebrovascular events: evidence from a large, multicenter, cross-sectional survey in Italy (MIRACLES study)

OBJECTIVES: To estimate the prevalence of hypertension-migraine comorbidity; to determine their demographic and clinical characteristics versus patients with hypertension or migraine alone; and to see whether a history of cerebrovascular events was more common in the comorbidity group. METHODS: The MIRACLES, multicenter, cross-sectional, survey included 2973 patients with a known diagnosis of hypertension or migraine in a general practitioner setting in Italy. RESULTS: Five hundred and seventeen patients (17%) suffered from hypertension-migraine comorbidity, whereas 1271 (43%) suffered from hypertension only, and 1185 (40%) from migraine only. In the comorbidity group, the onset of comorbidity occurred at about 45 years of age, with migraine starting significantly later than in the migraine-only group, and hypertension significantly before than in the hypertension-only group; a familial history of both hypertension and migraine had a significantly higher frequency as compared with the hypertension and migraine group. Compared to hypertension (3.1%) and migraine (0.7%), the comorbidity group had a higher prevalence (4.4%) of history of cerebrovascular events, with an odds ratio of a predicted history of stroke/transient ischemic attack (TIA) of 1.76 [95% confidence interval (CI) 1.01-3.07] compared to the hypertension group. In patients without other recognized risk factors for stroke, stroke/TIA occurred more frequently in the comorbidity group, compared to the hypertension group. In the age range 40-49 years, prevalence of history of stroke/TIA was five-fold greater (4.8% in comorbidity vs. 0.9% in hypertension group). CONCLUSION: This cross-sectional study indicates that the prevalence of comorbidity hypertension-migraine is substantial and that patients with comorbidity have a higher probability of history of cerebrovascular events, compared to hypertensive patient