Two Hemoglobin Genes in Arabidopsis thaliana: The Evolutionary Origins of Leghemoglobins

We cloned two hemoglobin genes from Arabidopsis thaliana. One gene, AHB1, is related in sequence to the family of nonsymbiotic hemoglobin genes previously identified in a number of plant species (class 1). The second hemoglobin gene, AHB2, represents a class of nonsymbiotic hemoglobin (class 2) rela...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1997-10, Vol.94 (22), p.12230-12234
Main Authors: Trevaskis, B, Watts, R A, Andersson, C R, Llewellyn, D J, Hargrove, M S, Olson, J S, Dennis, E S, Peacock, W J
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Anaerobiosis
Arabidopsis - genetics
Arabidopsis Proteins
Biological Sciences
Botany
Cloning, Molecular
Evolution
Evolution, Molecular
Flowers & plants
Gene Expression Regulation, Plant
Genes
Genes, Plant
Hemoglobin
Hemoglobins
Hemoglobins - genetics
Hemoglobins - metabolism
Hypoxia
Leghemoglobin - genetics
Legumes
Molecular Sequence Data
Oxygen
Oxygen - metabolism
Plant Proteins - genetics
Plant roots
Plant Roots - metabolism
Plants
RNA
Sequence Analysis, DNA
Sequence Homology, Amino Acid
Soybeans
Space life sciences
Symbiosis
Tissue Distribution
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Summary:We cloned two hemoglobin genes from Arabidopsis thaliana. One gene, AHB1, is related in sequence to the family of nonsymbiotic hemoglobin genes previously identified in a number of plant species (class 1). The second hemoglobin gene, AHB2, represents a class of nonsymbiotic hemoglobin (class 2) related in sequence to the symbiotic hemoglobin genes of legumes and Casuarina. The properties of these two hemoglobins suggest that the two families of nonsymbiotic hemoglobins may differ in function from each other and from the symbiotic hemoglobins. AHB1 is induced, in both roots and rosette leaves, by low oxygen levels. Recombinant AHB1 has an oxygen affinity so high as to make it unlikely to function as an oxygen transporter. AHB2 is expressed at a low level in rosette leaves and is low temperature-inducible. AHB2 protein has a lower affinity for oxygen than AHB1 but is similar to AHB1 in having an unusually low, pH-sensitive oxygen off-rate.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.94.22.12230