PHYSICAL AND STRUCTURAL CHARACTERIZATION OF YERSINIOPHORE, A SIDEROPHORE PRODUCED BY CLINICAL ISOLATES OF YERSINIA-ENTEROCOLITICA

Clinical isolates of Yersinia enterocolitca, which belong to mouse-let hal serotypes, produce the siderophore yersiniophore. Siderophore prod uction was shown to be iron regulated and to reach maximum production in late log phase. Yersiniophore is a fluorescent siderophore with max imum excitation at 270 nm and a major emission peak at 428 nm. Absorpt ion maxima were seen at 210 and 250 nm with a low broad peak from 280 to 320 nm, Purification of unchelated yersiniophore for structural ana lysis was made difficult by low yields (1-2 mg mg(-1)), and susceptibi lity to acid hydrolysis, oxidation and possibly polymerization. Yersin ophore was therefore purified as an Al3+ chelate, which was found to b e stable in solution for several weeks. To purify Al3+-yersiniophore, unchelated yersiniophore was first extracted from culture supernatants with dichloromethane, concentrated by rotary evaporation and adsorbed to a DEAE-sephacel column. Al3+-yersiniophore was eluted with 0.01 M AlCl3 and further purified by HPLC. The structure was established by a combination of elemental analysis, high resolution mass spectrometry and two-dimensional NMR experiments. Yersiniophore is a phenolate-thia zole siderophore with the formula C21H24N3O4S3Al and a molecular weigh t of 505.07404 when chelated to Al3+. The structure of yersiniophore w as determined to be closely related to the structures of pyochelin, pr oduced by Pseudomonas aeruginosa, and anguibactin, produced by Vibi to anguillarum.