Correlations between oxygen affinity and sequence classifications of plant hemoglobins

Smagghe, BJ; Hoy, JA; Percifield, R; Kundu, S; Hargrove, MS; Sarath, G; Hilbert, JL; Watts, RA; Dennis, ES; Peacock, WJ; Dewilde, S; Moens, L; Blouin, GC; Olson, JS; Appleby, CA

Correlations between oxygen affinity and sequence classifications of plant hemoglobins

Smagghe, BJ Hoy, JA Percifield, R Kundu, S Hargrove, MS Sarath, G Hilbert, JL Watts, RA Dennis, ES

Peacock, WJ

Dewilde, S Moens, L Blouin, GC Olson, JS Appleby, CA

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Publication Type:: Journal Article
Citation:: Biopolymers - Peptide Science Section, 2009, 91 (12), pp. 1083 - 1096
Issue Date:: 2009-12-16

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Field	Value	Language
dc.contributor.author	Smagghe, BJ	en_US
dc.contributor.author	Hoy, JA	en_US
dc.contributor.author	Percifield, R	en_US
dc.contributor.author	Kundu, S	en_US
dc.contributor.author	Hargrove, MS	en_US
dc.contributor.author	Sarath, G	en_US
dc.contributor.author	Hilbert, JL	en_US
dc.contributor.author	Watts, RA	en_US
dc.contributor.author	Dennis, ES https://orcid.org/0000-0002-7850-591X	en_US
dc.contributor.author	Peacock, WJ https://orcid.org/0000-0001-7314-9074	en_US
dc.contributor.author	Dewilde, S	en_US
dc.contributor.author	Moens, L	en_US
dc.contributor.author	Blouin, GC	en_US
dc.contributor.author	Olson, JS	en_US
dc.contributor.author	Appleby, CA	en_US
dc.date.issued	2009-12-16	en_US
dc.identifier.citation	Biopolymers - Peptide Science Section, 2009, 91 (12), pp. 1083 - 1096	en_US
dc.identifier.issn	0006-3525	en_US
dc.identifier.uri	http://hdl.handle.net/10453/28705
dc.description.abstract	Plants express three phylogenetic classes of hemoglobins (Hb) based on sequence analyses. Class 1 and 2 Hbs are full-length globins with the classical eight helix Mb-like fold, whereas Class 3 plant Hbs resemble the truncated globins found in bacteria. With the exception of the specialized leghemoglobins, the physiological functions of these plant hemoglobins remain unknown. We have reviewed and, in some cases, measured new oxygen binding properties of a large number of Class 1 and 2 plant nonsymbiotic Hbs and leghemoglobins. We found that sequence classification correlates with distinct extents of hexacoordination with the distal histidine and markedly different overall oxygen affinities and association and dissociation rate constants. These results suggest strong selective pressure for the evolution of distinct physiological functions. The leghemoglobins evolved from the Class 2 globins and show no hexacoordination, very high rates of O2 binding (∼250 μM-1 s -1), moderately high rates of O2 dissociation (∼5-15 s-1), and high oxygen affinity (Kd or P50 ≈ 50 nM). These properties both facilitate O2 diffusion to respiring N2 fixing bacteria and reduce O2 tension in the root nodules of legumes. The Class 1 plant Hbs show weak hexacoordination (K HisE7 ≈ 2), moderate rates of O2 binding (∼25 μM-1 s-1), very small rates of O2 dissociation (∼0.16 s-1), and remarkably high O2 affinities (P50 ≈ 2 nM), suggesting a function involving O 2 and nitric oxide (NO) scavenging. The Class 2 Hbs exhibit strong hexacoordination (KHisE7 ≈ 100), low rates of O2 binding (∼1 μM-1 s-1), moderately low O2 dissociation rate constants (∼1 s-1), and moderate, Mb-like O2 affinities (P50 ≈ 340 nM), perhaps suggesting a sensing role for sustained low, micromolar levels of oxygen. © 2009 Wiley Periodicals, Inc.	en_US
dc.relation.ispartof	Biopolymers - Peptide Science Section	en_US
dc.relation.isbasedon	10.1002/bip.21256	en_US
dc.subject.classification	Biophysics	en_US
dc.subject.mesh	Plants	en_US
dc.subject.mesh	Oxygen	en_US
dc.subject.mesh	Heme	en_US
dc.subject.mesh	Leghemoglobin	en_US
dc.subject.mesh	Plant Proteins	en_US
dc.subject.mesh	Recombinant Proteins	en_US
dc.subject.mesh	Crystallography, X-Ray	en_US
dc.subject.mesh	Spectroscopy, Fourier Transform Infrared	en_US
dc.subject.mesh	Phylogeny	en_US
dc.subject.mesh	Binding Sites	en_US
dc.subject.mesh	Binding, Competitive	en_US
dc.subject.mesh	Protein Structure, Tertiary	en_US
dc.subject.mesh	Protein Binding	en_US
dc.subject.mesh	Kinetics	en_US
dc.subject.mesh	Models, Molecular	en_US
dc.subject.mesh	Review Literature as Topic	en_US
dc.title	Correlations between oxygen affinity and sequence classifications of plant hemoglobins	en_US
dc.type	Journal Article
utslib.citation.volume	12	en_US
utslib.citation.volume	91	en_US
utslib.for	0607 Plant Biology	en_US
utslib.for	03 Chemical Sciences	en_US
utslib.for	06 Biological Sciences	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
utslib.copyright.status	closed_access
pubs.issue	12	en_US
pubs.publication-status	Published	en_US
pubs.volume	91	en_US

Abstract:

Plants express three phylogenetic classes of hemoglobins (Hb) based on sequence analyses. Class 1 and 2 Hbs are full-length globins with the classical eight helix Mb-like fold, whereas Class 3 plant Hbs resemble the truncated globins found in bacteria. With the exception of the specialized leghemoglobins, the physiological functions of these plant hemoglobins remain unknown. We have reviewed and, in some cases, measured new oxygen binding properties of a large number of Class 1 and 2 plant nonsymbiotic Hbs and leghemoglobins. We found that sequence classification correlates with distinct extents of hexacoordination with the distal histidine and markedly different overall oxygen affinities and association and dissociation rate constants. These results suggest strong selective pressure for the evolution of distinct physiological functions. The leghemoglobins evolved from the Class 2 globins and show no hexacoordination, very high rates of O2 binding (∼250 μM-1 s -1), moderately high rates of O2 dissociation (∼5-15 s-1), and high oxygen affinity (Kd or P50 ≈ 50 nM). These properties both facilitate O2 diffusion to respiring N2 fixing bacteria and reduce O2 tension in the root nodules of legumes. The Class 1 plant Hbs show weak hexacoordination (K HisE7 ≈ 2), moderate rates of O2 binding (∼25 μM-1 s-1), very small rates of O2 dissociation (∼0.16 s-1), and remarkably high O2 affinities (P50 ≈ 2 nM), suggesting a function involving O 2 and nitric oxide (NO) scavenging. The Class 2 Hbs exhibit strong hexacoordination (KHisE7 ≈ 100), low rates of O2 binding (∼1 μM-1 s-1), moderately low O2 dissociation rate constants (∼1 s-1), and moderate, Mb-like O2 affinities (P50 ≈ 340 nM), perhaps suggesting a sensing role for sustained low, micromolar levels of oxygen. © 2009 Wiley Periodicals, Inc.

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