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Oxygen binding to Arabidopsis thaliana AHb2 nonsymbiotic hemoglobin: evidence for a role in oxygen transport
Author(s) -
Spyrakis Francesca,
Bruno Stefano,
BidonChanal Axel,
Luque Francisco Javier,
Abbruzzetti Stefania,
Viappiani Cristiano,
Dominici Paola,
Mozzarelli Andrea
Publication year - 2011
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1002/iub.470
Subject(s) - arabidopsis thaliana , autoxidation , hemoglobin , oxygen transport , oxygen , mutant , p50 , chemistry , biophysics , biochemistry , biology , gene , organic chemistry , transcription factor
Abstract Nonsymbiotic 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 p 50 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 . © 2011 IUBMB IUBMB Life, 63(5): 363–362, 2011.