A hemoglobin from plants homologous to truncated hemoglobins of microorganisms.
Proc Natl Acad Sci U S A
; 98(18): 10119-24, 2001 Aug 28.
Article
de En
| MEDLINE
| ID: mdl-11526234
ABSTRACT
We have identified a nuclear-encoded Hb from plants (GLB3) that has a central domain similar to the "truncated" Hbs of bacteria, protozoa, and algae. The three-dimensional structure of these Hbs is a 2-on-2 arrangement of alpha-helices, distinct from the 3-on-3 arrangement of the standard globin fold [Pesce, A., Couture, M., Dewilde, S., Guertin, M., Yamauchi, K., Ascenzi, P., Moens, L. & Bolognesi, M. (2000) EMBO J. 19, 2424-2434]. GLB3-like genes are not found in animals or yeast, but our analysis reveals that they are present in a wide range of Angiosperms and a Bryophyte. Although cyanobacteria and Chlamydomonas have 2-on-2 Hbs (GLBN), GLB3 is more likely related to GLBO-type 2-on-2 Hbs from bacteria. Consequently, GLB3 is unlikely to have arisen from a horizontal transfer between the chloroplast and nuclear genomes. Arabidopsis thaliana GLB3 protein exhibits unusual concentration-independent binding of O(2) and CO. The absorbance spectrum of deoxy-GLB3 is unique; the protein forms a transient six-coordinate structure after reduction and deoxygenation, which slowly converts to a five-coordinate structure. In A. thaliana, GLB3 is expressed throughout the plant but responds to none of the treatments that induce plant 3-on-3 Hbs. Our analysis of the sequence, ligand interactions, and expression profile of GLB3 indicates that this protein has unique biochemical properties, evolutionary history, and, most likely, a function distinct from those of other plant Hbs.
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Protéines végétales
/
Plantes
/
Hémoglobines
Type d'étude:
Prognostic_studies
Limites:
Animals
Langue:
En
Journal:
Proc Natl Acad Sci U S A
Année:
2001
Type de document:
Article
Pays d'affiliation:
Australie