Zebrafish reveals different and conserved features of vertebrate neuroglobin gene structure, expression pattern, and ligand binding.
Neuroglobin has been identified as a respiratory protein that is primarily expressed in the mammalian nervous system. Here we present the first detailed analysis of neuroglobin from a non-mammalian vertebrate, the zebrafish Danio rerio. The zebrafish neuroglobin gene reveals a mammalian-type exon-intron pattern in the coding region (B12.2, E11.0, and G7.0), plus an additional 5'-non-coding exon. Similar to the mammalian neuroglobin, the zebrafish protein displays a hexacoordinate deoxy-binding scheme. Flash photolysis kinetics show the competitive binding on the millisecond timescale of external ligands and the distal histidine, resulting in an oxygen affinity of 1 torr. Western blotting, immune staining, and mRNA in situ hybridization demonstrate neuroglobin expression in the fish central nervous system and the retina but also in the gills. Neurons containing neuroglobin have a widespread distribution in the brain but are also present in the olfactory system. In the fish retina, neuroglobin is mainly present in the inner segments of the photoreceptor cells. In the gills, the chloride cells were identified to express neuroglobin. Neuroglobin appears to be associated with mitochondria-rich cell types and thus oxygen consumption rates, suggesting a myoglobin-like function of this protein in facilitated oxygen diffusion.
Fuchs
Christine
C
Institute of Molecular Genetics, Johannes Gutenberg University of Mainz, D-55099 Mainz, Germany.
Heib
Valeska
V
Kiger
Laurent
L
Haberkamp
Mark
M
Roesner
Anja
A
Schmidt
Marc
M
Hamdane
Djemel
D
Marden
Michael C
MC
Hankeln
Thomas
T
Burmester
Thorsten
T
D000818:Animals; D001667:Binding, Competitive; D015153:Blotting, Western; D002712:Chlorides / Q000737:chemistry; D003001:Cloning, Molecular; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000378:metabolism; D004058:Diffusion; D005091:Exons; D005786:Gene Expression Regulation; D005880:Gills / Q000378:metabolism; D005914:Globins / Q000235:genetics*; D006639:Histidine / Q000737:chemistry; D017403:In Situ Hybridization; D007438:Introns; D007700:Kinetics; D008024:Ligands; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism; D008957:Models, Genetic; D009419:Nerve Tissue Proteins / Q000235:genetics*; D000078787:Neuroglobin; D009833:Olfactory Pathways / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D012160:Retina / Q000378:metabolism; D013053:Spectrophotometry; D015027:Zebrafish
D002712:Chlorides; D018076:DNA, Complementary; D008024:Ligands; D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D012333:RNA, Messenger; D011994:Recombinant Proteins; D006639:Histidine; D005914:Globins; D010100:Oxygen