Protein chemotaxonomy of genus Datura: identical amino acid sequence of ferredoxin from two varieties of Datura stramonium

[Bioinorganic Chemistry of Iron]

　The X-ray crystallographic analysis of the single-crystal mugineic acid-Cu(II) complex showed that mugineic acid acts as a hexadentate ligand. Mugineic acid, a typical phytosiderophore, shows a marked stimulating effect on ⁵⁹Fe-uptake and chlorophyll synthesis in rice plants. A salient feature is the higher reduction potential of the mugineic acid-Fe(III) complex than those of bacterial siderophores. X-ray diffraction study of the structurally analogous Co(III) complex of the mugineic acid-Fe(III) complex demonstrates that the azetidine nitrogen and secondary amine nitrogen, and both terminal carboxylate oxygens, coordinate as basal planar donors, and the hydroxyl oxygen and intermediate carboxylate oxygen bind as axial donors in a nearly octahedral configuration. The iron-transport mechanism in gramineous plants appears to involve the excretion of mugineic acid from the roots, which aids Fe(III)-solubilization and reduction of Fe(III) to Fe(II). Manganese peroxidase (MnP) is a component of the lignin degradation system of the basidiomycetous fungus, Phanerochaete chrysosporium. To elucidate the heme environment of this novel Mn(II)-dependent extracellular enzyme, we studied its ESR and resonance Raman spectroscopic properties. Consequently, it is most likely that the heme environment of MnP resembles that of cytochrome c peroxidase. In addition, degradation methods using basidiomycetous fungi or Fe³⁺-H₂O₂ mixed reagent were developed for dioxins and polychlorinated biphenyls. The complete amino acid sequences of respective [2Fe-2S] ferredoxins were determined and compared with those of other higher plants. Finally, the toxic effects of iron on human health and the development of novel antibacterial drugs capable of inhibiting the iron transport system of Vibrio vulnificus are described.

Protein Chemotaxonomy. XIII. Amino Acid Sequence of Ferredoxin from Panax ginseng

The complete amino acid sequence of [2Fe-2S] ferredoxin from Panax ginseng (Araliaceae) has been determined by automated Edman degradation of the entire S-carboxymethylcysteinyl protein and of the peptides obtained by enzymatic digestion. This ferredoxin has a unique amino acid sequence, which includes an insertion of Tyr at the 3rd position from the amino-terminus and a deletion of two amino acid residues at the carboxyl terminus. This ferredoxin had 18 differences in its amino acid sequence compared to that of Petroselinum sativum (Umbelliferae). In contrast, 23-33 differences were observed compared to other dicotyledonous plants. This suggests that Panax ginseng is related taxonomically to umbelliferous plants.

Amino acid sequences of ferredoxins from Atropa belladonna and Hyoscyamus niger: their similarities to those in other tropane-alkaloid-containing plants

The complete amino acid sequences of [2Fe-2S] ferredoxin from Atropa belladonna and Hyoscyamus niger have been determined by automated Edman degradation of the entire S-carboxymethylcysteinyl proteins and of the peptides obtained by enzymatic digestion. These two ferredoxins exhibited 1-8 differences in their amino acid sequences compared to those of other tropane-alkaloid-containing plants (Scopolia japonica, Datura stramonium, D. metel, and D. arborea), and only 1 or 4 differences compared to S. japonica and D. arborea. In contrast, 9-23 differences were observed among the other solanaceous ferredoxins. This suggests that tropane-alkaloid-containing plants are closely related taxonomically.

Comparison of the Nucleotide Sequences of Ferredoxin-cDNAs among some Datura Plants

The nucleotide sequences of partial ferredoxin (Fd)-cDNAs (corresponding to the amino acid sequence of 22-87 in the total 97 amino acids of ferredoxin) were determined for Datura arborea, D. stramonium, D. metel, and related Datura plants. Non-synonymous substitutions were noted at 4 positions and a synonymous substitution was seen at position 82 (Gln [CAA] (arborea) vs. Gln [CAG] (stramonium and metel)). The nucleotide sequence of Fd-cDNA may provide more detailed information regarding the relative taxonomic positions of plants than the amino acid sequence. However, Datura plants in the same section (metel, fastuosa, and innoxia) and of different varieties (stramonium var. stramonium and stramonium var. tatula) showed identical Fd-cDNA nucleotide sequences. This result suggests that there are very close relationships among the plants in each group.

Large differences in amino acid sequences among ferredoxins from several species of genus Solanum

The complete amino acid sequences of [2Fe-2S] ferredoxins from four species of genus Solanum (S. nigrum, S. lyratum, S. indicum, and S. abutiloides) were determined by automated Edman degradation of the entire S-carboxymethylcysteinyl proteins and of the peptides obtained by enzymatic digestion. The amino acid sequences of these four ferredoxins differed from each other by 12-19, whereas 0-4 differences have been observed among ferredoxins from plants in the same genus and 14-40 differences were seen between different families. This suggests that these Solanum plants are distantly related to each other taxonomically.

Amino acid sequences of ferredoxins from Scopolia japonica and Lycium chinense: their similarities to that of Datura arborea

The complete amino acid sequences of [2Fe-2S] ferredoxins from Scopolia japonica and Lycium chinense have been determined by automated Edman degradation of the entire Cm-proteins and of the peptides obtained by enzymatic digestions. These two ferredoxins exhibited only 2-7 differences in the amino acid sequence when compared to the Datura-ferredoxins (D. stramonium, D. metel, and D. arborea), and especially only 2 or 3 differences compared to D. arborea. On the contrary, 8-19 differences were observed among the other solanaceous ferredoxins. This suggests that S. japonica and L. chinense are closely related taxonomically to Datura plants, especially to D. arborea.

Amino acid sequence of ferredoxin from Physalis alkekengi var. francheti

The complete amino acid sequence of [2Fe-2S] ferredoxin from Physalis alkekengi var. francheti has been determined by automated Edman degradation of the entire Cm-protein and of the peptides obtained by trypsin and endoproteinase Asp-N digestions. This ferredoxin exhibited ten, ten, and nine differences respectively in the amino acid sequence, when compared with the ferredoxins of Datura stramonium, D. metel, and D. arborea, but 21-28 differences for other angiosperms, and 34-37 differences for fern and horsetails. These results are in harmony with the taxonomic position for these plants.

Amino acid sequence of ferredoxin from Datura arborea

The complete amino acid sequence of [2Fe-2S] ferredoxin from Datura arborea, "Tree Datura", has been determined by automated Edman degradation of the entire Cm-protein and of the peptides obtained by tryptic digestion and CNBr treatment. The D. arborea ferredoxin exhibited three and four differences, respectively, in the amino acid sequences when compared with the ferredoxins of D. stramonium and D. metel (herbaceous species). This result supports the idea of Bernhardi and Safford that 'Tree Datura' such as D. arborea should be considered as one section of the genus Datura and not a separate genus.

Identical amino acid sequence of ferredoxin from Datura metel and D. innoxia

The complete amino acid sequence of the respective [2Fe-2S] ferredoxins from Datura metel (D. alba) and D. innoxia, have been determined by automated Edman degradation of the entire Cm-protein and of the peptides obtained by tryptic digestion and CNBr treatment. The ferredoxins from the two plants had an identical amino acid sequence, suggesting a very close taxonomic relationship between the two. This is the first report for the identical primary structure of Fds from different species of higher plants.