| Abstract
| - The biosynthetic pathway of 3-amino-5-hydroxybenzoicacid (AHBA) formation was studied with cell-free extracts from the rifamycin B producer, Amycolatopsismediterranei S699, and the ansatrienin A producer,Streptomyces collinus Tü1892. Phosphoenolpyruvate(PEP) plus erythrose 4-phosphate (E4P) gave AHBA in lowbut nevertheless significant (6%) yield.3,4-Dideoxy-4-amino-d-arabino-heptulosonicacid 7-phosphate (aminoDAHP)was converted efficiently into AHBA (45%), as were5-deoxy-5-amino-3-dehydroquinic acid (aminoDHQ, 41%)and 5-deoxy-5-amino-3-dehydroshikimic acid (aminoDHS, 95%). Onthe other hand, the normal shikimate pathwayintermediate, 3-deoxy-d-arabino-heptulosonicacid 7-phosphate (DAHP) did not give rise to AHBA undertheseconditions. AminoDAHP (9%) was produced by incubation of[14C]PEP and E4P, but not of[14C]DAHP, with thecell-free extracts. The results demonstrate the operation of a newvariant of the shikimate pathway in the formationof the mC7N units of ansamycin, and presumably alsomitomycin, antibiotics which leads from PEP, E4P, and anitrogen source directly to aminoDAHP and then via aminoDHQ andaminoDHS to AHBA.
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