Rhizobium japonicum Rhizobitoxin

These enol ether-substituted amino acids are natural products isolated from the fermentation broths of Rhizobium japonicum (rhizobitoxine) (31), Pseudomonas aeruginosa (methoxy analogue) (33) and a species of Streptomvces (ethoxy analogue) (34). 

A similar peptide toxin, rhizobitoxin (16), is produced by the root-nodulating organism Rhizobium japonicum. Rhizobitoxin causes chlorosis in the developing leaflets of plants, such as soybean Glycine max), which have nodules colonized with these strains of Rhizobium japonicum (Mitchell, 1981). This compound is a irreversible inhibitor of ethylene production from methionine, as it blocks the conversion... 

There are only a few instances in which amino acids have been implicated in allelopathy and in most cases the specific amino acids have not been identified. Rhizobitoxine is produced by certain strains of Rhizobium japonicum and is a nonprotein amino acid (84). Several of the phytotoxins produced by pathogenic microorganisms are polypeptides and related glycopeptides (82). 

A phytotoxin from the nodules produced by Rhizobium japonicum on the roots of soybean (Glycine max (L.) Merr.), termed rhizobitoxine, was identified by Owens et al. (231, 232, 233) as 2-amino.4-(2-amino-3-hydroxypropyl)-trans-but-3-enoic acid. Another closely related analog of rhizobitoxine,... 

Many naturally occurring irreversible enzyme inhibitors also exist. These are referred to as toxins. A well-known and intriguing toxin is the / ,y-unsaturated amino acid rhizobitoxine, produced by Rhizobium japonicum. This natural metabolite is a highly specific irreversible inhibitor of pyridoxal-hnked jS-cystathionase from bacteria and plants (318). 

Rhizobitoxine, an analogue of cystathionine produced by certain strains of Rhizobium japonicum (Owens et al., 1972), is a potent irreversible inhibitor of plant cystathionine 8-lyase both in vivo (Giovanelli et al., 1973) and in vitro. Inhibition of the purified spinach enzyme was of the active-site-directed irreversible type (Giovanelli et al., 1971), and probably involves covalent linkage of a cleavage product of rhizobitoxine to the pyridoxal phosphate prosthetic group of the enzyme. 

Structure of rhizobitoxine, an antimetabolite enol-ether amino acid from Rhizobium japonicum, J. Chem. Soc. Chem. 

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