Home › Publications

Oxygen binding to Arabidopsis thaliana AHb2 nonsymbiotic hemoglobin: evidence for a role in oxygen transport

Posted November 16th, 2011 by xbarril
TitleOxygen binding to Arabidopsis thaliana AHb2 nonsymbiotic hemoglobin: evidence for a role in oxygen transport
Publication TypeJournal Article
Year of Publication2011
AuthorsSpyrakis, F, Bruno S, Bidon-Chanal A, Luque FJ, Abbruzzetti S, Viappiani C, Dominici P, Mozzarelli A
JournalIUBMB life
Volume63
Issue5
Pagination355 - 362
Date Published2011/05//
KeywordsArabidopsis/physiology; Arabidopsis Proteins/chemistry/genetics/metabolism; Biological Transport; Hemoglobins/chemistry/genetics/metabolism; Models, Molecular; Molecular Dynamics Simulation; Oxidation-Reduction; Oxygen/metabolism; Protein Binding; Protein Conformation
AbstractNonsymbiotic hemoglobins AHb1 and AHb2 discovered in Arabidopsis thaliana are likely to carry out distinct physiological roles, in consideration of their differences in sequence, structure, expression pattern, and tissue localization. Despite a relatively fast autoxidation in the presence of O(2) , we were able to collect O(2) -binding curves for AHb2 in the presence of a reduction enzymatic system. AHb2 binds O(2) noncooperatively with a p50 of 0.021 +/- 0.003 Torr, a value consistent with a recently proposed role in O(2) transport. The analysis of the internal cavities derived from the structures sampled in molecular dynamics simulations confirms strong differences with AHb1, proposed to work as a NO deoxygenase in vivo. Overall, our results are consistent with a role for AHb2 as an oxygen carrier, as recently proposed on the basis of experiments on AHb2-overexpressing mutants of A. thaliana.