Inter- and intra-molecular interactions of Arabidopsis thaliana DELLA protein RGL1.

The phytohormone gibberellin and the DELLA proteins act together to control key aspects of plant development. Gibberellin induces degradation of DELLA proteins by recruitment of an F-box protein using a molecular switch: a gibberellin-bound nuclear receptor interacts with the N-terminal domain of DELLA proteins, and this event primes the DELLA C-terminal domain for interaction with the F-box protein. However, the mechanism of signalling between the N- and C-terminal domains of DELLA proteins is unresolved. In the present study, we used in vivo and in vitro approaches to characterize di- and tri-partite interactions of the DELLA protein RGL1 (REPRESSOR OF GA1-3-LIKE 1) of Arabidopsis thaliana with the gibberellin receptor GID1A (GIBBERELLIC ACID-INSENSITIVE DWARF-1A) and the F-box protein SLY1 (SLEEPY1). Deuterium-exchange MS unequivocally showed that the entire N-terminal domain of RGL1 is disordered prior to interaction with the GID1A; furthermore, association/dissociation kinetics, determined by surface plasmon resonance, predicts a two-state conformational change of the RGL1 N-terminal domain upon interaction with GID1A. Additionally, competition assays with monoclonal antibodies revealed that contacts mediated by the short helix Asp-Glu-Leu-Leu of the hallmark DELLA motif are not essential for the GID1A-RGL1 N-terminal domain interaction. Finally, yeast two- and three-hybrid experiments determined that unabated communication between N- and C-terminal domains of RGL1 is required for recruitment of the F-box protein SLY1.

Lack of effect of seasonal trivalent influenza vaccine against influenza A(H3N2) infections in hospitalised patients in winter 2012.

AIM: This study sought to assess the effectiveness of the 2012 trivalent inactivated influenza vaccine in preventing admission with confirmed influenza A(H3N2) infection and whether vaccination status influenced the duration or outcome. METHODS: We used the CDHB Delphic Laboratory Information System to identify 100 consecutive patients with confirmed influenza A(H3N2) infection. The patients were contacted via telephone and asked whether they had received the seasonal influenza vaccine prior to their hospital admission. We collected information such as age, gender, documented co-morbidities, smoking status, ICU admission, length of stay, and final outcome of admission and compared these between the vaccinated and non-vaccinated groups. RESULTS: A total of 92 participants could be contacted and participated; 67 these reported having been vaccinated with the 2012 seasonal influenza vaccine prior to their admission. There were no significant differences in length of stay or final outcome in vaccinated and non-vaccinated patients. CONCLUSION: This audit shows that the 2012 seasonal influenza vaccine did not provide significant protection against the H3N2 influenza strain in Canterbury. Vaccination did not alter the clinical course or final outcome in patients infected with H3N2 influenza.