METABOLITES OF ERWINIA .10. METABOLISM OF POLYAMINES AND BASIC-AMINO-ACIDS IN ERWINIA-AMYLOVORA - APPLICATION OF LIQUID-CHROMATOGRAPHY ELECTROSPRAY MASS-SPECTROMETRY TO PROFERRIOXAMINE PRECURSOR FEEDING AND INHIBITION STUDIES

Erwinia amylovora, the etiological agent of fire blight, produces a fa mily of proferrioxamine siderophores, which may be essential for the p athogen to establish itself in its hosts, If so, then control of fire blight may perhaps be possible via interference with proferrioxamine b iosynthesis. Proof of this hypothesis requires prior knowledge of the corresponding biosynthetic pathways in E. amylovora, As a first step t owards understanding proferrioxamine biosynthesis, it was of interest to investigate the ability of the fire blight bacterium to utilize var ious potential biosynthetic pathways for diamines, Feeding of lysine, ornithine and diaminobutyric acid gave rise to highly elevated levels of cadaverine, putrescine and diaminopropane, respectively, indicating that the corresponding decarboxylase activities are all present in E. amylovora, The conclusion for lysine decarboxylase was confirmed with (N-15(2))lysine, which was converted to (N-15(2))cadaverine. Arginine did not increase putrescine levels substantially, but (C-13(6))argini ne nevertheless gave rise to (C-13(4))putrescine while suppressing exc retion of non-labeled putrescine, A serendipitous result of this study was the finding that the growth of E, amylovora can be inhibited with 5-hydroxylysine and 1,4-diamino-2-butanone. The mechanism of inhibiti on appears complex and is not yet understood, For 5-hydroxylysine, pre liminary investigations point to a competitive inhibition of lysine de carboxylase, However, the growth inhibition cannot be reversed by prov iding cadaverine, the decarboxylation product of lysine,