Biosynthesis of the penicillin precursor -(L-( -aminoadipyl)-L-cysteinyl-D-valine (ACV) is catalyzed from the constituent L-amino acids and ATP by a multifunctional peptide synthetase (ACV synthetase, ACVS). Its structure basically consists of three modules, each containing key motifs involved in ATP-binding, acyladenylate formation and aminoacylation. The modules have been tentatively associated with activation of the respective amino acids in order of their sequence in the peptide, and this association has been proved by limited proteolysis for the middle domain activating cysteine. Investigation on the substrate specificities of the other modules has been approached by fragment expression. We here present data on the third module thought to activate L-valine. The adenylate region has been subcloned and is expressed in Aspergillus nidulans. Unexpectedly also -aminoadipic acid forms an adenylate.
Full conference title:
3rd EUROPEAN CONFERENCE ON FUNGAL GENETICS
- ECFG 3rd (1996)