STRUCTURE AND CHARACTERIZATION OF ISOPYOVERDIN FROM PSEUDOMONAS-PUTIDA BTP1 AND ITS RELATION TO THE BIOGENETIC PATHWAY LEADING TO PYOVERDINS

Pyoverdin type siderophores produced by six fluorescent Pseudomonas st rains isolated from different rhizospheres were purified and character ized. The purified ferri-pyoverdins were tested for their ability to p romote the growth of other strains grown under iron deficiency conditi ons. Only the one obtained from Pseudomonas putida BTP1 did not act as a growth promoter. The structure of the BTP1 siderophore was elucidat ed by spectroscopic methods and degradation studies. It turned out tha t it contains a chromophore which differs from the one typical for pyo verdins insofar as it carries the carboxyl group in 3- rather than in 1-position 5-amino-1,2-dihydro-8,9-dihydroxy-3H-pyrimidol[1,2 a] quino line-3-carboxylic acid). The amino group of the chromophore is substit uted with the fi-carboxyl group of L-glutamic acid and its carboxyl gr oup with the N-terminus of the peptide Ala-L-Asp-D-N-5-AC-N-5-OH-Orn-L -Ser-L-c-N-5-OH-Om. This isopyoverdin fits into the biogenetic scheme which postulates ferribactins as the precursors of pyoverdins.