Title
Correlations between oxygen affinity and sequence classifications of plant hemoglobins
Author
Faculty/Department
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences . Biomedical Sciences
Publication type
article
Publication
New York ,
Subject
Physics
Chemistry
Biology
Source (journal)
Biopolymers. - New York
Volume/pages
91(2009) :12 , p. 1083-1096
ISSN
0006-3525
ISI
000270961600012
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
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 O(2) binding (similar to 250 mu M(-1) s(-1)), moderately high rates of O(2) dissociation (similar to 5-15 s(-1)), and high oxygen affinity (K(d) or P(50) approximate to 50 nM). These properties both facilitate O(2) diffusion to respiring N(2) fixing bacteria and reduce O(2) tension in the root nodules of legumes. The Class 1 plant Hbs show weak hexacoordination (K(HisE7) approximate to 2), moderate rates of O(2) binding (similar to 25 mu M(-1) s(-1)), very small rates of O(2) dissociation (similar to 0.16 s(-1)), and remarkably high O(2) affinities (P(50) approximate to 2 nM), suggesting a function involving O(2) and nitric oxide (NO) scavenging. The Class 2 Hbs exhibit strong hexacoordination (K(HisE7) approximate to 100), low rates of O(2) binding (similar to 1 mu M(-1) s(-1)), moderately low O(2) dissociation rate constants (similar to 1 s(-1)), and moderate, Mb-like O(2) affinities (P(50) approximate to 340 nM), perhaps suggesting a sensing role for sustained low, micromolar levels of oxygen. (c) 2009 Wiley Periodicals, Inc. Biopolymers 91: 1083-1096, 2009.
E-info
https://repository.uantwerpen.be/docman/iruaauth/8c36d5/e671178.pdf
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000270961600012&DestLinkType=RelatedRecords&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000270961600012&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000270961600012&DestLinkType=CitingArticles&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
Handle