Isopyoverdin Pp BTP 1, a Biogenetically Interesting Novel Siderophore fromPseudomonas putida

From the cultures of Pseudomonas putida BTP 1 a siderophore could be isolated which contains the chromophore 2a rather than 1a typical for pyoverdins. Its structure was elucidated by MS, NMR and chemical degradation. This new structural type is of great interest: The currently accepted biogenetic pathway leading to 1a starts from D-Tyr and L-Dab which condense to give the ferribactin chromophore 4. Subsequent ring closure via the α-nitrogen of Dab leads to 1a while the alternative ring closure via the γ-nitrogen would yield 2a. It is for the first time that this isochromophore has been detected in a Pseudomonas siderophore. Its discovery confirms the assumed intermediacy of ferribactins in the biogenesis of pyoverdins.