| Popis: |
The final steps in the biosynthesis of the antifungal peptidyl-nucleoside blasticidin S ( 3 ) have been revised to include a novel self-resistance mechanism wherein the previously proposed final precursor, demethylblasticidin S ( 7 ), is modified with a leucine residue yielding leucyldemethylblasticidin S ( 10 ) which exhibits reduced antibiotic activity. Methylation of 10 yields leucylblasticidin S ( 9 ) which can be exported from the bacterium and hydrolyzed to 3 . Also disclosed is the finding of a blasticidin S N -acetyltransferase activity that may function to detoxify 3 and 7 inadvertently produced prior to export or which gain reentry to the cell. |
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